22 G. O. Sars. 



the present form. It is certainly very nearly related to 

 Jurine's species, but in my opinion is specifically distinct, 

 differing in the much more depressed head, the evenly 

 curved fornix, and the somewhat different sculpture of 

 the shell. 



Occurrence. — Only a few female specimens of 

 this form were secured. They were found in one of my 

 aquaria prepared with mud from Itatiba, and were at once 

 recognizable from the other species, C. Bigaudi, likewise 

 occurring in the aquarium, by their larger size and more 

 greenish colour. The specimens examined by Mr. Kichard 

 were collected by Dr. v. Ihering at San Lorenço, likewise 

 in Brazil. 



Gen. Simocephalus, Schoedeler. 

 Remarks. — This genus seems to be represented 

 in all parts of the world. Besides the 2 South American 

 species treated of below, another species has recently been 

 described by Dr. Vavra from Chili as S inflatus. More- 

 over a species, S. cacicus is recorded by Mr. Moniez from 

 Lake Titikaka; but it is so imperfectly described as scarcely 

 to be recognizable. The 2 well-known European species, S. 

 exspinosus de Geer and S. vetulus Müll, have also resently 

 been recorded from South America, though in this case some 

 doubt may arise as to the correctness of the identification. 

 The 2 species described below are both easily recognizable 

 from the European forms. 



