1851.] 227 



furnished upon each side of the anal aperture with four unequal, compreBsed, 

 oval, curved, contractile, vibrillated appendages. Upper lip triangular. (Esopha- 

 gus passing to sixth annulation. 



Length 2 to 6 lines; breadth anteriorly 1-lOth line; middle l-8th line; caudal 

 annulation expanded l-5th line. Lip l-250th in. long. Setae l-666th in. to 

 l-133d in. long. 



Hub, Living in tubes of mud or decayed vegetable particles, upon the bottom 

 of stagnant ponds and ditches, in the neighborhood of Philadelphia. 



It is usually observed with the posterior half or two-thirds of its body 

 projecting nearly vertically from its tube, with the caudal, contractile ap- 

 pendages expanded. Upon any disturbance it rapidly retreats within its tube. 

 A sessile species of vorticella is frequently found attached to the posterior part of 

 the body. 



At first sight there appears to be only three appendages each side of the anus, 

 but closer examination proves the existence of a fourth, small and not so dis- 

 tinct. 



Dr. Leidy, on behalf of the Curators, stated that he desired to cor- 

 rect an error which he had noticed in a report of some remarks by 

 Mr. Squier at a meeting of the American Ethnographical Society, in 

 which Mr. S. stated that Dr. Morton's collection of Crania had been 

 presented to the Academy. Dr. Leidy had ascertained from Dr. 

 Morton's Executors, that the collection had not been presented to this 

 Institution. 



ELECTION OP MEMBERS. 



Caspar Wistar, M. D., and Mr. Charles E. Smith, of Philadelphia, 

 were elected Members of the Academy. 



