Dr. Baird on new species of Entozoa. 69 



who transmitted it to the Museum. It may be only a variety of 

 H. Jlavilabris, but the nuchal and post-vertebral shields are very 

 differently shaped. 



4. Hydraspis Spixii, Gray, Cat. Kept. B. M. 30. 



Shell oblong, depressed ; middle of the back flat ; marginal shields 

 very broad in front, narrow and bent up on the sides, broader and 

 arched over the hind legs ; the post-vertebral shield large, as wide as 

 long ; third and fourth narrow, longer than broad ; the fourth and 

 fifth with an acute keel on the hinder edge ; sternum rather broad ; 

 head very large, crown and temples covered with small shields ; ears 

 prominent ; neck smooth ; lower part of the outer edge of the hind 

 leg with four larger plates, the last compressed and largest. 



Hab. Brazils, Para. 



There is an adult stuffed specimen, and a skeleton of nearly the 

 same size, of this species in the British Museum collection. 



This species is very like //. gihba, but the back is more depressed, 

 the margin much wider, the head nearly double the size, compared 

 with the size of the body, and the scales on the head are small, more 

 numerous and more equal in size, and those on the edge of the hinder 

 legs are larger and more equal in size. 



Fam. 3. Trionycid^.. 



Cyclanorbis Petersii. 



Shell broad, rounded before and behind ; sternal callosities five. 



Hab. West Africa, River Gambia. 



This genus was proposed by Dr. Peters, on his return from Mo- 

 zambique, for a soft Tortoise which he discovered in that country, 

 which has flaps to the sides of the sternum, covering the legs like the 

 Amy dee of Asia, but differs from these in having no bones on the mar- 

 gin of the dorsal disk, which is soft and flexible as in the Trionyces 

 with exposed legs. 



This species from the Gambia appears to be distinct from the one 

 noticed by Dr. Peters in Mozambique ; I have therefore named it 

 after that excellent naturalist, who has made such sacrifices for the 

 extension of our knowledge of natural history, and of zoology in par- 

 ticular. 



February 8, 1853.— John Gould, Esq., F.R.S., in the Chair. 



Descriptions of some New Species of Entozoa from 



THE Collection of the British Museum. 



By W. Baird, M.D., F.L.S. 



Class Entozoa. Order Nematoidea. 



Family AscARiDiE. 



Genus Ascaris. 

 1. Ascaris similis. 



Ascaris similis, Baird, Cat. Entoz. Brit. Mus. 19. t. I. f. 1. 

 Head small ; mouth with three small valves slightly projecting be- 



