RESEARCHES IN HELMINTHOLOGY AND PARASITOLOGY. IO9 



Dr. Will. A. Hammond, 525 miles west of Fort Riley, Kansas Ter- 

 ritory. Dr. Hammond states they were found in a pond in great 

 numbers, in company with Sircdon. They swam actively forward 

 an inch or two beneath the surface of the water, and occasionally 

 lifted the anterior end even above the latter. 



The collection contains 24 females and the same number of males. 

 The females are cylindrical, light brown of various shades, shining, 

 iridescent ; anterior extremely narrowed ; head surrounded with a 

 dark-brown ring ; tail obtuse, slightly compressed, with a terminal 

 genital pore. The males are darker colored than the females ; tail 

 extremity more or less spirally enrolled, with the extremit}^ bifur- 

 cated ; forks divergent, incurved, smooth, connected at base ante- 

 riorly b}' a crescentic fold, in advance of which is the genital pore ; 

 head as in the female. 



The females measure from 10 inches in length by i-3d of a line 

 thick, to two feet 6 inches in length and 3-5ths of a line thick ; the 

 males S inches in length by i-4th of a line thick, to 2 feet 2 inches 

 ill length by 2-5ths of a line thick. 



Dr. Leidy next directed the attention of the members to a bottle 

 containing seven specimens of the larva of a species of Oestrus or 

 bot-fly. They were obtained by Dr. Hammond from a pouched rat, 

 Thomomys borcalis, at Bridger's Pass, on the summit of the Rocky 

 mountains, July, 1857. Dr. Hammond found the rat panting on 

 the road side, without power of escaping. The bots were found 

 .situated beneath the .skin of the back, belly, and thigh. 



The body of these larvae is oblong oval, compressed, incurved ; 

 head minute, composed of a transverse pair of papillary eminences, 

 each supporting two minute ocelli, and having projecting from 

 beneath, forward and downward, a pair of .strong black hooks. 

 Spiracular laminae trilobed and marked with vermicular lines. 

 Segments of the body clo.sely covered with discoidal corneous 

 tubercles, of which the anterior ones have their posterior border 

 projecting and dentated. 



The .smallest is light yellowish brown, and as they become larger 

 they assume a darker tint. The largest are black, hard, .shining, 

 and remarkably shagreened in appearance. 



lycngth of the smallest larva 5 lines, breadth 3 lines, thickness ly-z 

 lines ; length of largest 9 lines, breadth 5^2 lines, thickness 3 lines. 



[April, 1858. No. 197. See Bibliography.] 



Dr. Leidy called the attention of the members to a drawing of a 

 curious worm, which he said was obtained from the Schuylkill 



