140 



PROCEEDINGS OF THE NATIONAL MUSEUM. 



VOL. 39. 



Aomm 

 Fig. 1.— Head of dog tapeworm. 



head attached is hereby designated as the type-specimen and lias 



been entered in the Helminthological Collection of the U. S. National 



Museum as No. 7314. A specimen without the head is designated 



as the paratype and has been entered in the same collection as No. 



7315. The longest specimen collected is 

 headless and is 24 cm. long. 



Wliile proglottids were still being found 

 in the feces of this dog, a post-mortem 

 examination of a lynx, Lynx rufus macu- 

 latus, from southern New Mexico disclosed 

 the existence of a very 

 recent tapeworm in- 

 fection indicated by 

 the presence of a num- 

 ber of tapeworm heads 

 with a neck, but no 

 segments as yet devel- 

 oped. The heads were 

 apparently of the same 

 species as the one ob- 

 tained from the dog. 



In fact, certain peculiar characteristics leave little 



room for doubt on this point. Not only is the 



general shape of the head the same, but the form 



and dimensions of the hooks and the suckers are 



the same and there is the same tendency to lose 



the large hooks. It is further evident from a 



study of the tapeworms from both hosts that the 



parasite is a new species of the genus Txnia and 



the name Tsenia halaniceps is here proposed 



for it. 



As the specific name indicates, the shape of 



the head resembles to some extent that of an 



acorn, due to the very prominent rostellum 



which projects anterior of the suckers much as 



the seed of the acorn projects from its cup. The 



rostellum, being a protrusible muscular organ, is 



not of constant dimensions. In the head of the 



tapeworm collected from the dog and mounted 



in balsam (fig. 1), the distance from the anterior 



edge of the sucker to the tip of the rostellum is 



300 /( and the maximum breadth of the head is 668 //. The entire 



length of the head in this specimen can not be accurately measured 



owing to the contracted condition of the neck. In a specimen 



unm. 





,>?tf"^ 





wi* ^: 



,w^-!4 



^{m 



■,iin 



XM 



Fig. 2.— Head of ltnx 

 tapeworm. 



collected from the lynx and mounted in glycerine (fig. 2), the distance 



