RESEARCHES IN HELMINTHOLOGV AND PARASITOLOGY. 7 



of the ventricle of the heart. The pericardium wa.s perfectly tran.s- 

 parent, and presented no appearance of cicatrix, or marks of exter- 

 nal communication. Dr. Leidy then read the following descrip- 

 tion of 



Distoma hclicis. — Oval, flattened, white in colour ; oral disk large, 

 round, marked by radiating lines : posterior disk central, about the 

 size of that of the mouth, radiate, with a dark spot in the center. 

 Intestinal canal commencing by a fusiform oesophagus, the apex of 

 which joins a round stomachal cavit}-, from which passes off on each 

 side a convoluted intestinum, which proceeds to the posterior ex- 

 tremity of the body. About half way between the central disk and 

 the posterior extremity of the animal, I indistinctly observed w^hat 

 I presumed to be the generative orifice. 



[August, 1847. No. 20. See Bibliography.] 



Dr. Leidy requested permission, which was given, to change the 

 name of a new genus of Entozoa, described by him in Vol. 3, No. 5, 

 of the Proceedings, from that of Cryptobia to Cryptoicus, the former 

 name having been preoccupied. 



DESCRIPTION AND ANATOMY OF A NEW AND CURIOUS SUBGENUS 



OF PLANARIA. 



In October, 1840, Prof. S. S. Haldeman published a description 

 of an animal under the name of Planaria gracilis/'^ Upon examina- 

 tion I detected such a remarkable peculiarity in the digestive appa- 

 ratus as led me to investigate its anatomy in detail, and to form 

 for it a separate subgenus, characterized as follows : 



Phagocata, oblonga, plano-convexa, nuda, contractilis, muscosa, 

 antica auricularia. Aperturae duae, ventrales, ad os et generationem 

 pertinens. Proboscides multse. 



P. gracilis, nigricans, lateribus parallelis, postero acuto abrupte, 

 plerumque antico recto; oculis duobus. Long., 9 lin. ; lat., i lin. 

 Habitat in fontis Pennsylvaniae. 



Description. — Oblong, limaceform, naked, convex superiorly, fiat 

 inferiorh" very contractile ; sides ordinarily parallel, convex when the 

 animal is in a contracted state, convergent anteriorly w^hen elongated ; 

 anterior extremity with a lateral triangular auricular appendage, 



* Supplement to number one of "A Monograph of the Ivimniades, or Fresh- 

 water Univalve Shells of North America, "containing descriptions of apparently 

 hew animals in different classes. &c. ByS. S. Hakieman. Philadelphia, 1840. 



