ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 893 



characters and takes on a form adapted to its medium ; the hosts 

 experimented on were Bana temporaria and Tropidonotus natrix. M. 

 Ercolani finds, as has Mr. A. P. Thomas, that the ova do not undergo 

 any development during the cold of winter. 



Distomum of the Crayfish.* — Prof, G. Zaddach reports that several 

 years ago he found a number of cysts of Distomum cirrigerum in cray- 

 fishes ; his attention was first directed to them by the peculiar 

 characters of their testes on which he saw blackish spots ; they were 

 afterwards observed in greater number in the muscles of the post- 

 abdomen, where they ordinarily lay near the surface. Notwith- 

 standing their presence the infested crayfishes were found to be 

 perfectly healthy, and the author points out that the evil effects of 

 trichinosis are only effected when the parasite wanders, and so sets up 

 nerve-irritation ; the migrations of the Cercariae, on the other hand, 

 seem in no way to affect the health of their hosts ; and the same is 

 generally true of the other Trematode parasite, D. isosfomum. The 

 author enters into a detailed examination of the characters and habits 

 of these forms, and comes to the somewhat remarkable conclusion 

 that in D. isostomum two sexually mature forms succeed one another. 



Urinary Apparatus and Blood-lymph Spaces of the Platodes.f 



— Prof. E. Van Beneden points out that the results of Fraipont's 

 investigations lead to the demonstration of a system of spaces, which 

 is independent of the canalicular system of Eay Lankester, and which 

 was unknown to that naturalist ; from this it follows that the cana- 

 licular system must not be regarded as a coelom as well as the 

 urinary apparatus, but as the latter of these only. 



New Rotifers. — Mr. H. F. Atwood describes and figures J a 

 Brachionus which he considers to be new. It was found in a filtering 

 of Hemlock Lake water, and the name of B. Conium is proposed 

 for it : — 



"Lorica irregularly truncate, slightly reticulated over entire 

 surface, except the collar carrying frontal spines ; this latter portion 

 has a hard vitreous appearance. 



" Ten frontal spines, the middle one on the dorsal surface longer 

 than the balance, and describing almost a right angle turn near its 

 centre to one side. This spine half as long as the carapace of the 

 rotifer ; eye-spot prominent ; no openings on dorsal surface of 

 carapace. 



" Four posterior spines, one at either extreme side, and one on 

 either side of anal opening. Tail, or foot, slender and bifid. Extreme 

 length of rotifer, including anterior and posterior spines, y^^q of 

 an inch." 



Unfortunately a dead specimen had to be used for the drawing, 

 hence no definite description can be given of mouth-parts for internal 

 structure. The external appearance is, however, so strikingly charac- 



* Zool. Anzeig., iv. (1881) pp. 398-404, 426-31. 



t Ibid., pp. 455-9. 



X Science, ii. (1881) p. 235 (2 figs.). 



