ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 595 



pared for by the accumulation in each of the posterior segments of four 

 special histogenetic masses, situated between the muscular bundles and 

 the ccelomic endothelium. At the maximum development, these masses, 

 formed of yellowish cells, distend the rings of the Serpulid and protrude 

 like a hernia into the body-cavity. This histogenetic material occupies 

 precisely the same place as the sex-cells occupy in the sexual individuals. 

 The material for proliferation is homologous with the sexual material. 



Integumentary Structures of Sipunculids.* — Marcel A. Herubel 

 has made a comparative study of the papillae, spines, and hooks of 

 Sipunculids. A group of hooks never co-exists with a group of spines ; 

 all the hooks of any one species belong to the same type ; the papillae 

 are almost generically constant ; the papillae and hooks are most de- 

 veloped in species from the warmer waters. 



New Species of Echiurus. f — A. Skorikow refers to two specimens of 

 an Echiurus obtained in 1902 by the ' Puritan ' near Capri, from a 

 depth of 1100-1500 metres or more. Lo Bianco named them Echiurus 

 pallasi, but Skorikow doubts if this species occurs in the Mediterranean. 

 An examination of the specimens showed that they differ from E. pallasi 

 Pall (or more correctly E. echiurus Pall.), e.g. in the relatively large 

 and distinct funnel of the segmental organ. 



Blood-vessels of Rhynchobdellids.f — Emily Arnesen has studied 

 Branchellion, Pontobdella, Glossiphonia, and other leeches with reference 

 to the fine structure of the blood-vessels. She has given particular- 

 attention to the dorsal blood-vessel and its valves. The lining of the 

 vessels consists of an internal muscular and a median connective-tissue 

 layer, which is covered externally by ccelomic epithelium (Kowalevsky's 

 "cellules acides"). The muscular layer consists of muscle-cells which 

 are to begin with of the same type as those in the rest of the body. 

 The valves seem to arise as pouch-like invaginations of the corners 

 between the septal lamellae and the wall of the blood-vessel. It is prob- 

 able, as Kupffer suggested, that they form blood corpuscles. 



Oogenesis of Branchellion.§ — Ch. Perez and E. Gendre report some 

 interesting phenomena in the oogenesis of this specialised leech. In 

 the germinal portion of the ovary the cells are found in groups of two, 

 one within the other. The external cell distends into a sort of shell, 

 the internal cell forms a spherical morula. Among the uniform cells of 

 this morula one becomes central and increases in size. It is merely a 

 cytophore, however, for it is one of the superficial cells that increases 

 greatly in size and becomes the ovum. 



Nematohelminthes. 



Structure and Relationships of Gordiidse.jj — Max Rauther con- 

 cludes from his detailed anatomical study of Gordiidae that they are 

 nearly related to Annelids. Their structure sheds light on that of 



* Bull. Soc. Zool. France, xxx. (1905) pp. 90-97 (2 figs.). 



t Zool. Anzeig., xxix. (1905) pp. 217-21. 



j Jenaische Zeitschr. Naturwiss., xxxviii. (1905) pp. 771-806 (3 pis.). 



§ P. V. Soc. Sci. Bordeaux, 1904, pp. 108-9. 



|| Jenaische Zeitschr. Naturwiss., xl. (1905) pp. 1-94 (4 pis.). 



