摘要:

The later morphogenesis of the acrosome ofLimnodriloides winckelmanniandRhyacodrilus arthingtonaeis compared with that inEnchytraeusand in earthworms. After superposition of the acrosome on the tip of the nucleus the manchette continues apically beyond the nucleus to ensheath the acrosomal tube. At the posterior limit of, and probably contained in, the spacious/ terminal primary acrosomal vesicle is an electron‐dense ring. A domed protrusion into the floor of the primary vesicle is tentatively regarded as the secondary acrosome vesicle. The axial rod when first observed is attached to the vesicle complex. Later, the rod detaches and extends deeply into the acrosome tube. A membrane ensheathes the tubificid axial rod but its exact homology with the complex layers surrounding the lumbricid or megascolecid axial rod is not clear. The domed apical region of the tubificid acrosome is probably a persistence of the primary acrosome vesicle and it is deduced that the acrosome vesicle surrounding the axial rod in lumbricids and megascolecids is a product, by invagination, of the secondary acrosome vesicle onl

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00593.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The statistical distribution of labelled nuclei in the shell‐field ofMytilus galloprovincialisafter introduction of3H‐thymidine shows that there is no growth center in the shell producing epithelium in bivalves, as in gastropods. In contrast the shell‐field grows by mitotic cell division which occurs in all zones. Thus it is evident that the individual cells of the shell‐field always remain in the same region. As in gastropods various permanently differentiated zones must be held responsible for the secretion of the different shell

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00594.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Topotype material ofPustulopora pustulosa(Goldfuss), the type species ofPustuloporaBlainville, is investigated and its structure described. It has a distinctive budding pattern in which autozooecia are formed from an axial bundle of zooecia. The gonozooecium is of ‘Mecynoecia’‐

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00595.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The odontodes of some of the palatal dermal bones inBoreosomus piveteauiNielsen tend to form odontocomplexes, e.g. symmetrical areal ones where some degree of superimposition may occur between ganoin layers belonging to the component odontodes, and asymmetrical areal ones where this is quite insignificant. In the areal odontocomplexes of the dermal bones inPlegmolepissp., the degree of overlap between the corresponding layers is somewhat more pronounced. Finally, in the areal odontocomplexes of the dermal bones inGyrolepiscf.albertiiAgassiz, we have a more advanced stage of phyletic specialization where each of the ganoin layers of the component odontodes lies directly superimposed on the preceding one throughout the extent of the latter. At the same time, the effect of phyletic dentine reduction is clearly noticeable here by the development of “extra” ganoin layers no more retaining their original connections with that hard tissue (also developed in the scalesof Plegmolepissp.). Remarks are i.a. given on the characters by whichAcropholis and Plegmolepisare said to be distinguishable from each ot

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00596.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Actinoscyphia saginata(Verrill, 1882; type species) andActinoscyphia aurelia(Stephenson, 1918) are redescribed with special reference to characters of diagnostic significance in order to differentiate the two species both inhabiting the 2000 m slope region of the North Atlantic. In situ photograph ofA. aureliaoff the North West African coast shows it to display a novel life form type in expanding its bi‐lobed tentacular disc like a Venus‐fly‐trap and standing on the muddy sediment with a small, non‐adhesive base penetrating just below the surface of the sediment. The peculiar nematocyst equipment found in both species makes it necessary to rehabilitate the family Actinoscyphiidae Stephenson, 1920. The systematic position of the family is discussed and eventually the Actinoscyphiidae is considered as sister group (sensu Hennig) of the Hormathiidae. Because of the loss of acontia in the Actinoscyphiidae, this taxon is considered to be the more advanced one.Chondrodactis japonicaWassilieff, 1908, is found to belong to the genusActino

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00597.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The body wall of the daughter sporocyst ofCercaria vaullegeardiPelseneer, 1906 is unusual for a species without a birth pore in consisting of an outer anucleated, microvillous syncytial tegument and a cellular subtegument which lacks secretory cells. In contrast, most other known daughter sporocysts without birth pores have a nucleated region above the microvillous region of the tegument. The significance and functional aspects of this structure are discussed.

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00598.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

The family Microlaimidae contains Bolbolaiminae subfam.n.(Bolbolaimussyn.Pseudomicro‐laimus)and Microlaiminae (Calomicrolaimus, IxonemaandMicrolaimus). The new family Molgolaimidae contains Aponematinae subfam.n. (Aponemagen.n.) and Molgolaiminae subfam.n. (MolgolaimusandProdesmodora). The main differentiating characters applied are: structures of the head region, shape of the oesophagus, position of the excretory pore, shape of the tail, structure of the gonads and ornamentation of the cuticle. The significance of porids and preanal supplements as distinguishing characters is, discussed. Microlaimidae are closely related to Desmodoridae; Molgolaimidae related to Spiriniidae.Paramicrolaimusis transferred from Microlaimidae to Spiriniidae.–Six species from the Øresund, Denmark, are redescribed:Microlaimus punctulatusGerlach, 1950 andM. acinacesWarwick&Piatt, 1973;Aponema torosus(Lorenzen, 1973) gen.n., comb.n. (syn.Microlaimus torosusLoren‐zen, 1973);Molgolaimus allgeni(Gerlach, 1950) comb.n. (syn.Microlaimus allgeniGerlach, 1950) andM. turgofrons(Lorenzen, 1972) comb.n. (syn.Microlaimus turgofronsLorenzen, 1972);Paramicrolaimus spiruliferWieser

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00599.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Filamentous organs, termed metanemes and interpreted as stretch receptor organs, have been discovered in nematodes of the order Enoplida. They have not been found in species of 11 other nematode orders. According to light microscopical observations, a metaneme consists of a 5–15 μm long scapulus, a 20–400 μm long frontal and a 30–170 μm long caudal cuticularized filament; the latter is lacking in some taxa. Metanemes are arranged serially in the lateral epidermal cords; they are parallel or at an angle of 10–30° to the longitudinal body line. The function of metanemes is likely to coordinate the serpentine movement and to control the actual

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00600.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Valvognathia pogonostomagen. et sp.n. is described as belonging to the family Onychognathiidae Sterrer, 1972. An integrated picture of the jaw apparatus is presented, based on interference phase contrast (Nomarski) and electron microscopy. The teeth are shown to be continuous with lamellae, apophyses, fibulae, and even jugum. These structures are all extracellular secretions covering the apical surfaces of the jaw apparatus epithelium. They constitute a single, interconnected, “cuticular” structure. Spiral‐ciliary‐organs and rhabditoid organelles are described in the ep

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00601.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY

摘要:

Re‐examination of 35 species and some “varieties” has led to a division of the whole “Peloscolex” complex of species into eight genera,PeloscolexLeidy, 1850,SpirospermaEisen, 1879,EmbolocephalusRandolph, 1892,Orientodrilusgen.n.,Baikalodrilusgen.n.,Habergen.n.,Edukemiusgen.n., andTubificoidesLastochkin, 1937. This division is based first and foremost on the construction and histology of the male genital organs, but it is also supported by other charac

ISSN:0300-3256    

DOI:10.1111/j.1463-6409.1978.tb00602.x

出版商:Blackwell Publishing Ltd    

年代:1978

数据来源: WILEY