248 [Aug., 1847. 



Meeting for Business, Aug. 31, 1847. 



Mr. Cassin in the Chair. 



The Committee on the following papers by Dr. Leidy, read 

 17th and 24th inst., reported in favour of publication in the 

 Proceedings. 



Description and Anatomy of anew and curious sub-genus of Planaria. 



By Joseph Leidy, M. D. 



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

 an animal under the name of Planaria gracilis.* Upon examination 

 I detected such a remarkable peculiarity in the digestive apparatus 

 as led me to investigate its anatomy in detail, and to form for it a 

 separate snb-genus, characterised as follows : 



Phagocala, oblonga, plano-convexa, nuda, contractus, mucosa, 

 antica auricularia. Apertura; duoe, ventrales, ad os et generationem 

 pertinens. Proboscides multse. 



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

 plerumque antico recto ; oculis duobus. Long. 91in.,lat. llin. Hab- 

 itat in fontibus Pennsylvania?. 



Description. Oblong, limaceform, naked, convex superiorly, flat 

 inferiorly, very contractile ; sides ordinarily parallel, convex when the 

 animal is in a contracted state, convergent anteriorly when elongated ; 

 anterior extremity with a lateral triangular auricular appendage, 

 straight in front, by contraction becoming convex or concave ; poste- 

 rior extremity abruptly pointed ; ocelli two, anterior composed of an 

 oblong, semi-transparent (nervous?) mass with an intensely black dot 

 of pigmentum at the internal posterior part ; ventral apertures two; 

 oral aperture a little less than one-third the length of the body from 

 the posterior extremity, and very dilatable ; generative aperture half- 

 way between the oral aperture and posterior extremity. Colour black 

 or iron gray, and some younger specimens latericeous. 



This animal I have only found in abundance in the neighborhood of 

 Prof. Haldeman's residence, near Columbia, Pa. In a spring in front 

 of his house, thousands of them may be seen gliding along the bottom; 

 some of them occasionally creep up the sides to the surface of the 



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

 water Univalve Shells of North America," containing descriptions of ap- 

 parently new animals in different classes, &c. ' t By S. S. Haldeman. Phila 

 delphia., 1840. 



