ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 587 



H. marsiliensis differ so strikingly from the other members of that genus, 

 that it is necessary to place them in the new genus Genostoma. The 

 diagnosis of the new genus is as follows : — Cilia confined to the ventral 

 surface, mouth-opening ventral at or near the posterior extremity, ovary 

 and yolk-gland united, male and female ducts opening into the anterior 

 end of the pharyngeal pocket. The genus must be placed in a sub- 

 family (Vorticina parasitica) of the family Vorticida ; and to the same 

 sub-family belongs a new form found in the mantle-cavity of Mytilus 

 edulis. This form is described as Urastoma fausseki g. et sp. n., the 

 generic characters being as follows : — Cilia equally distributed over the 

 whole surface, mouth opening at the posterior end of the body, " yolk "- 

 gland and ovary distinct, male and female ducts opening into the prox- 

 imal part of the pharyngeal pocket. Another new form was found in the 

 gut of Phascolosoma vulgare, and is described as Collastoma monorchia, 

 g. et sp. n. In it the pharynx is doliiform, the testes are compact and 

 unpaired, paired ovaries and yolk-glands are present, and there is a 

 large bursa seminalis communicating with the oviduct. The oviduct 

 represents only a part of the atrium genitale. Full descriptions of all 

 these forms are given. 



Maturation of Oocyte in Thysanozoon brocchi.* — R. Schockaert 

 has discovered a new structure — " un organite nouveau " — in the oocyte 

 of the first order in the Planarian named above. It is a delicate filament, 

 pointed at both ends, and quite distinct from the chromatin-coil. But 

 what gives it particular interest is that the author believes he has suc- 

 ceeded in showing that it gives origin to the centrosome. 



Peculiar Northern Nemerteans.f — Prof. Bergendal describes, from 

 the Swedish west coast, Callinera biirgeri g. et sp. n., related to the 

 CarmellidaB, but differing widely in external appearance, absence of 

 cerebral organs, structure of brain and gut, and above all, as regards pro- 

 boscis and rhynchoccelom ; and Gononemertes parasitica g. et sp. n., found 

 parasitic on Phallmia, and showing direct or indirect adaptations to 

 parasitism in the absence of eyes, the weak development of cephalic slits 

 and cerebral organ, and the great development of gonads. The short- 

 ness of the posterior proboscis region, the occurrence of an atrium into 

 which proboscis and fore-gut open, and finally, the slight development 

 of the caecum, are further peculiarities which make the position of 

 Gononemertes among the Metauemertines very uncertain. 



New Nemertines.J — Herr E. Isler describes a number of new species 

 of Amphiporus, Eupolia, Lineus, and Cerebratulus. 



Incertae Sedis. 



Arctic Polyzoa.§ — Mr. A. W. Waters has been entrusted with the 

 Polyzoa collected by the Jackson-Harmsworth Expedition in Franz-Josef 

 Land during 1896-97, and publishes descriptions of the Chilostomata, 

 with some notes on distribution. The collection includes 59 species, 

 and of these Rippotlwa hyalina is cosmopolitan, Porella concinna, Escha- 

 roides sarsii, and Gribrilina punctata are only very doubtfully found in 



* Anat. Anzeig., xviii. (1900) pp. 30-3 (6 figs.). 



t Zool. Anzeig., xxiii. (1900) pp. 313-28 (6 figs.). J Tom. cit., pp. 177-80 



§ Journ. Linn. Soc. (Zool.), xxviii. (1900) pp. 43-105 (6 pis.). 



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