ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 577 



elusion that the central structures in these elements are comparable to 

 centrioles. They are extraordinary in their large size, and in the 

 variability of their size, for dimensions of 4 /x-1 /x or less are recorded. 



Indian Oligochseta.* — W. Michaelsen gives an account of a large 

 collection from India, Xepal, Ceylon, Burma, and the Andaman Islands. 

 He distinguishes limnic Oligochajtes mostly belonging to the archaic 

 families of iEolosomatida? and Naidida?, one littoral form Pontodrilus 

 insidaris Rosa, from Ceylon, and the terrestrial forms which make up the 

 bulk of the collection. Among these he distinguishes the endemic 

 species from the " peregrine " species distributed by man. There is a 

 fine discussion of the geographical distribution and its bearing on 

 geological history. 



J. Stephenson "f gives an account of the structure of several fresh- 

 water forms belonging to the genera N~ais, Pristina, Slavina, and 

 StyJaria. He calls attention to the very variable thorn-like projections 

 on the dorsal seta? of several forms, to the probable sensory function of 

 the dorsal setae of the third segment of Pristina longiseta, and to the 

 variations in the length of the prostomium in Pristina. There is an 

 " antiperistaltic " action and reversed ciliary current in the intestine of 

 these aquatic forms, and this has probably a respiratory significance. 

 It is pointed out that sexual and asexual reproduction may occur con- 

 comitantly in Nais variabilis. 



Fresh-water Oligochaeta.ij: — W. Michaelsen gives a very useful and 

 very welcome guide to the study of the fresh-water OligochaBta of 

 Germany. 



Fresh-water Hirudinea.§ — L. Johansson gives an account of the 

 fresh-water leeches of Germany, which will be of much service to 

 students of the fresh-water fauna. 



New Australian Leech. || — E. J. Goddard describes Dineta cylindrica 

 g. et sp.n. from New South Wales. Its general appearance is not unlike 

 that of OrobcMla, and its structure is nearest that of Dina. 



Minute Structure of Vascular System in Branchiobdella.f — Fr. 

 Bilek has studied this in B. parasita Henle, with special reference to 

 the " vasochord " found in the intestinal sinus and in the dorsal blood- 

 vessel. It seems that vasochord, sinus, and vasothelium must be re- 

 ferred to an endodermic origin. In its youngest stages the vasochord 

 is seen in direct connection with the intestinal epithelium, differentiat- 

 ing from the supplementary cells. The vasochord was probably a me- 

 chanical function, securing that the lumen of the heart is narrowed as 

 much as possible during contraction, and to some extent compensating 

 for the absence of cardiac valves in Branchiobdella. 



* Memoirs Indian Museum, i. (1909) pp. 103-253 (2 pis.), 

 t Tom. cit., pp. 255-81 (6 pis.). 



X Die Siisswasserfauna Deutschlands. Herausgegeben von A. Brauer. Heft 13 

 <Jena, 1909, pp. 1-66 (112 figs.). § Tom. cit., pp. 67-81 (32 figs.). 



|| Proc. Linn. Soc. N.S.W., xxxiii. (1908) pp. 854-66 (2 pis.). 

 i Zool. Anzeig., xxxiii. (1908) pp. 466-73 (4 figs.). 



