ALBERT

Notes: Summary Trichopsis pumilus has the same system of sound production asTrichopsis vittatus but with morphological differents. As distinguished fromTrichopsis vittatus muscels and tendons of the sound producing mechanism in femals ofTrichopsis pumilus are very reduced. Therefore probable femals ofTrichopsis pumilus are not able to produce sounds.

Notes: Summary Various types of surface microstructures and their distribution in the Giant Antarctic SlaterGlyptonotus antarcticus Eights, 1852, are described in detail. Although no attempt has been made to classify the different kinds of scales, leaf-like modifications, threads and feathery hairs, ideas concerning their origin and their function are presented. At least some of the microstructures described seem involved in discouraging foraminifera and larval stages of sessile organisms to settle upon the cuticle ofClyptonotus.

Notes: Summary The ultrastructural features of oogenesis were examined in the spionid polychaeteStreblospio benedicti. Paired ovaries are attached to the genital blood vessels extending into the coelomic space from the circumintestinal sinus. The genital blood vessel wall is composed of flattened, peritoneal cells, large follicle cells and developing oocytes. Vitellogenesis occurs while the oocytes are attached to the blood vessel wall. Two morphologically distinguishable types of yolk are synthesized. Type I is synthesized first by an autosynthetic process apparently involving pinocytosis and the conjoined efforts of the Golgi complex and rough endoplasmic reticulum. Type II yolk appears later through a heterosynthetic process involving the infolding of the oolemma and the sequestering of materials from the blood vessel lumen by endocytosis. During this process, blood pigment molecules appear to be incorporated into endocytotic pits, vesicles and eventually the forming yolk body. The significance of heterosynthetic yolk formation to the general reproductive strategies of polychaetous annelids is discussed.

Notes: Summary An ocellus of an anthomedusan, Nemopsis dofleini, is composed of sensory and pigment cells and underlain by a nerve plexus and a muscle sheet. A sensory cell is divided into three parts: an apical part from which a single cilium arises, a slender middle part with numerous microtubules and an enlarged basal part that contains an oval nucleus but does not send out an axon. The ocellar cup is occupied by variously remodelled ciliary sheaths that are covered by a few lysosomal projections from the pigment cells. Three modes of synaptic connections — centripetal, centrifugal and two-way — are found between sensory cells and either dendrites or somata of second order neurons. Synaptic vesicles in sensory cells are larger in number, smaller in size and more uniform in shape than those of second order neurons. The soma of a second order neuron lies below the surface layer of an ocellar cup and gives rise to a single cilium that lacks rootlets and the second centriole. The possibility of multimodal sensory perception in and around the ocellar region is discussed.

Notes: Summary The whip organs are situated proximally on the ventral side of most segments of the whip scorpion's whip. As the cuticular layer covering these organs is much thinner than the usual cuticle, the whip organs may be recognized easily under the light microscope as oval regions. The study of the ultrastructure reveals an epithelium characterized by apical and basal invaginations of the cell membrane with numerous mitochondria and prominent whorls of smooth endoplasmic reticulum. Thus, the whip organs possess the characteristics required for transepithelial transport processes. The possible function is discussed, based on experimental study.

Notes: Summary Structure and ultrastructure of the papillae in the mantle epithelium of the polyplacophoranAcanthochiton fascicularis are described. They consist to a major part of various secretory cells. Visual cells occur frequently in the papillae. Each of these organs form up to a few spines which have basally a cup of organic material. This connects the calcareous spine with the spine cell and often with a second cell which has distally one cilium. They are tactile receptors. Other spines are only for the defense and can be moved by muscles. They continue to grow basally in contrast to the tactile spines which are pushed off after some time and replaced by new ones formed in the papillae. The aesthetes and the mantle papillae are homologous organs.

Notes: Summary The mature male nephridia ofPolydora ligni andP. websteri (Polychaeta: Spionidae) are segmental organs composed of a ciliated nephrostome connected to a nephridial canal that crosses the intersegmental septum, expands into a large modified part extending dorsally through the coelom and subsequently narrows into a canal terminating in a dorsal nephridiopore. The nephridial canal is ciliated throughout and is composed of several cell types. Cells in the expanded region of the nephridia of both species contain large urn-shaped depressions filled with long microvilli. InP. ligni, one section of a nephridium contains cells packed with electron-dense granules that are not observed inP. websteri. The spermatophores ofPolydora ligni are composed of a central sperm mass surrounded by a layer of randomly oriented tubules that form a capsule around the sperm and taper into a long thin tail. These tubules are identical in dimensions to the microvilli present in parts of a nephridium and apparently are derived from these microvilli. The spermatophore capsule ofP. websteri is composed of similar tubules also presumed to originate from nephridial microvilli. The microvilli in nephridia of both species are surrounded with a glycocalyx that may function as an adhesive to hold the spermatophore capsule together. This glycocalyx may also function as a species specific message when encountered by a receptive female.

Notes: Summary The internal and external structure of the galeae of the adult red turnip beetle, Entomoscelis americana, was studied using SEM and TEM. The galea broadens from base to truncated tip and its sides are of thick, sculpted cuticle invested with pores and coarse spines. The tip is of thinner, flexible cuticle covered with 8–12 uniporous, blunt-tipped apical pegs and a single, aporous, sharply-pointed apical hair. The coarse spines are singly innervated probable mechanosensilla owing to the tubular body at the distal end of the dendrite. These sensilla likely act as tactile hairs monitoring galeal-effected movements of food particles into the functional mouth. The pores are associated with glands within the galea. The function of the presumed secretion is not known but may be to keep objects and dried saliva from sticking to the mouthparts. The apical pegs are innervated by five neurons, each producing a single dendrite. Four dendrites enter the single peg lumen and communicate with the terminal pore. The fifth differentiates into a tubular body that inserts into the peg base. These are typical insect contact chemosensilla that, because of their location, would taste incoming food. The apical hair has no pores but is innervated by two neurons, each extending a dendrite into the hair lumen in chemosensillar fashion. The sensory mode of this sensillum is unknown but is probably not mechanoor chemoreception. Many of its features, reminiscent of taste hairs, lead us to hypothesize that it represents a one-time chemosensillum recently modified to a new form and sensory mode. Because larval and adult E. americana share similar food plant requirements, we hypothesize that similarities will be seen in their mouthpart sensilla. Comparisons of the adults and larvae show the common features between their respective galeal taste hairs are only those of insect contact chemosensilla in general. However, the adult apical hair and the larval medial sensillum show striking specific structural similarities. We propose that these are true structural and functional homologues.

Notes: Summary The wall of the sinus venosus in an elasmobranchian species, Chimaera monstrosa L. is described. Endocardial cells contain numerous large vacuoles, as well as a number of membrane-bounded, moderately electron dense bodies (MDB). Myocardial cells lie closely packed into bundles surrounded by a basal lamina of about 20 nm thickness, and by large amounts of collagen fibres. These cells are connected by desmosomes of 1–2 µm length and with an intermembranous gap of 10–20 nm. Myocardial cells poor in myofibrils are intermingled with cells containing a well developed contractile material. Atrial specific granules are scarce. Vesiculated nerve processes occur at a distance of about 20 nm from the myocardial sarcolemma. Myocardial cells of the sino-atrial junction appear ultrastructurally similar to those located elsewhere in the sinus venosus. Epicardial cells contain large vacuoles, and have fibrecoated protrusions extending into the pericardial space. The possibility of pacemaker activity in the elasmobranchian sinus venosus is discussed.

Notes: Summary The nature and homologues of the appendages of the anterior end of the polychaete families Sabellidae and Serpulidae have long been discussed. The main purpose of the present investigation, in which seven sabellid and eight serpulid species are studied, is to contribute towards the solution of these problems. At the same time, however, the present study, within its limited range, aims to enlarge our knowledge of the anatomy of the polychaetes in general. Such a knowledge, it is argued, is a prerequisite for further consideration of the phylogeny of the Polychaeta. As shown in many earlier papers, the architecture of the cephalic nervous system and the innervation of the organs and appendages of the anterior end of polychaetes constitute reliable instruments for elucidating the morphological significance of these structures. In the present paper, consequently, extra consideration is given to descriptions of the central nervous system of the sabellids and serpulids studied. The integumental depression found in front of and below the brain of all the sabellids and serpulids here studied is described by the term “dorsal pit”. It is concluded that the dorsal pit within each family in all probability represents a homologous structure, but it is in no way proven that the dorsal pit of the sabellids is equivalent to that of the serpulids. Some earlier literature maintains that paired antennae [antennes de première paire in Binard and Jennerś (1928) terminology] are found in some sabellids and serpulids. In the present paper it is maintained that these structures must instead be interpreted as nuchal organs. Such organs are found in all the sabellid and serpulid species here studied. The Pruvot-Meyer theory which claims that the joint pore of the thoracic nephridia of the “serpulimorphic” families is equivalent to the nuchal organ of other polychaetes is shown to be without foundation, and it is consequently rejected. The histology, vascularization, and innervation of the branchial crown and the appendages of the dorsal lip of the mouth of the species investigated are described. It is concluded that the branchial crown and some (but not all) appendages of the dorsal lip are equivalent to the palps (when present) of the “spiomorphic”, the “drilomorphic”, and the “errant” polychaetes. The appendages of the dorsal lip of the mouth, in most faunistic literature called palps, are found to represent structures of three different kinds and origins: (a) branchial radioli which have become separated from the crown and have fused with the lip, (b) branchial pinnulae which have undergone a similar process of dislocation, and (c) new formations from the walls of the mouth cavity. It is proposed that in comparative-anatomical works these appendages should be called (a) lip-associated radioli, (b) lip-associated pinnulae, and (c) outgrowths of the dorsal lip respectively. As a joint and anatomically neutral term to be used in faunas and descriptions of the outer morphology, the expression “appendages of the dorsal lip” or, more briefly, “(dorsal) lip processes” is proposed. The interrelationships of the Sabellariidae, the Sabellidae, and the Serpulidae are discussed, as is the taxonomic subdivision of the last two families. In agreement with some earlier authors although contrary to others it is thereby maintained that: 1) the suborder Serpulimorpha Hatschek (1893) (inclucing sabellariids, sabellids, and serpulids) does not constitute a natural systematic unit; 2) the sabellids and serpulids, although markedly different in many respects (thoracic membrane, operculum, branchial skeleton), are probably closely related to each other. Earlier arguments supporting this view are corroborated by data on the dorsal lip processes and the architecture of the brain of the two families; 3) Rioja's (1923) division (based on setal structures) of the Sabellidae into the three subfamilies Sabellinae, Fabriciinae, and Myxicolinae is supported by the anatomical data emphasized in the present paper; and 4) within the Serpulidae the genera Apomatus and Protula should be referred to the subfamily Filograninae [as proposed by Rioja (1923), followed, among others, by Fauvel (1927), and Hartmann-Schröder (1971)] and not to the Serpulinae, [as maintained by Hartman (1959) and Fauchald (1977)]. Again, the view presented by the present author is founded on anatomical data (the morphological value of the dorsal lip processes of the genera in question).