ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 317 



distance on the ventral aspect ; the single ventral ovary, almost as long 

 as the worm itself. The ova all ripen at the same time ; the early 

 development takes place within the body, which eventually becomes little 

 more than an elongated sac filled with eggs or embryos. The largest 

 specimen contained upwards of 20 million embryos. 



We may add to this report that a specimen of this interesting 

 parasite was recently obtained from a sea-urchin brought in by an 

 Aberdeen trawler. 



Platyh.elminth.es. 



Sexual Phases in Geonemertes.* — W. K. Coe finds that the Ber- 

 muda land Nemertean, Geonemertes ar/ricola, is not only hermaphrodite 

 but also viviparous. The sexual phases are further complicated by the 

 appearance of undifferentiated gonads which form both kinds of sexual 

 products. Such gonads often occur interspersed among others which 

 form either ova or spermatozoa only. As a rule in such an ovo-testis 

 the spermatozoa are discharged before the single ovum of the same 

 organ has matured. Self -fertilisation probably does not normally occur. 



Land Planarian from Ohio.| — L. B. Walton records the occurrence 

 or a species of Rliyncltodemus in Ohio. It differs in many particulars 

 from the only known form of this genus occurring in the United States, 

 although it is probably related to it. 



Two Interesting Trematodes.f — Norman Maclaren gives a full 

 description of (a) Dipl&ctanum cequans Diesing, a Gyrodactylid from the 

 gills of Labrax lupus, etc., which he refers to the genus Tetraonchus 

 Diesing, sub-genus DipJectanum, and (ft) Nematobothrium molce sp. n. 

 from the sunfish, which he refers to the Distomidse. 



Habits and Structure of Cotylaspis insignis.§ — H. L. Osbom has 

 investigated a number of points in the anatomy and habits of this 

 Trematode. In Lake Chautauqua it is confined to Anodonta, although 

 this is not the case with respect to the United States generally. It 

 most commonly occurs adhering very firmly by its huge ventral sucker 

 to the cloacal surface of the kidney of its host. It can hardly be 

 considered even ecto-parasitic, but is more strictly commensal, since 

 it not only does not draw any nutriment from its host, but is even 

 beneficial by keeping the surface of the kidney free from organic 

 material. The almost free habit would seem to be secondary, and 

 arrived at by way of a partially free ancestral form, having habits like 

 those of Aspidogaster. The excretory system is unlike that of any other 

 known member of the family. It has a single terminal dorsal pore, two 

 independent rhythmically pulsatile bladders, a collecting vessel running 

 directly to the level of the pharynx, ;i recurrent vessel, ciliated, directly 

 continuous with the collecting vessel, two branches from this — one 

 anterior and one posterior — into which all the larger capillary vessels 

 discharge, minute non-ciliated capillaries terminated by ciliated flarae- 



* Zool. Anzeig., xxviii. (190."".) pp. 454-8. 



t Ohio Naturalist, v. (1903) Xo. 3, p. 254. 



% Jcnaisnhe Zeitschr. Naturwiss., xxxviii. (1904) pp. 572-G18 (3 pis. and G fi^s.). 



§ Zool. Jahrb., xxi. (1904) pp. 201-35 (3 pis.). 



