NO. 1105. PBOCEEDIXafi OF THE XATTONAL MUSEUM. 169 



the viciuity of the female anlage — farthei- than this it could not be 

 traced. Tlie female organs gradually undergo a change, but this process 

 can not be described in detail because of lack of proper material. All 

 that it is at present safe to say is that a dark body of cells arises in the 

 vicinity of the receptaculuiu seminis and develops into the female glands 

 very similar to those found in the Tlertia of the porcupine; the uterus 

 gradually extends over the segment suppressing the genital glands. 



Eggs globular with three membranes, but pyriform body not visible; 

 outer membrane 40 to 42 u in diameter; middle membrane could not be 

 studied; inner niem])riine immediately surrounding the oncosphere 21 

 1.1 in diameter; hooks of oncosphere 9 /< long. ISTumerous small calca- 

 reous corpuscles present in the parenchyma. 



This worm has an entirely different appearance from the one found in 

 the porcupine and it is i)ossible that it will eventnally be raised to 

 specific rank. My material, however, does not warrant such a step at 

 present. 



The following is proposed as a diagnosis of the variety: 



.Diaf/uosis. — J>ertia americana leporis (Stiles, 1895), Stiles, 1896: 

 Strobila 23 to 47 mm. long by 5 to G.~> mm. broad, possessing from 60 

 to 95 segments. Head about O.G mm. broad by 0.4 to 0.6 mm. long, 

 unarmed; suckers large, about 0.2 mm. in diameter, unarmed. Neck 

 absent, stobilization beginning immediately back of the head. Genital 

 l)ores alternate, situated in about the middle of the lateral margin. 

 Genital organs develop very early, the male organs being visible some- 

 times as early as the sixth segment. Cirrus large and ( ? ) smooth. 

 Cirrus pouch about 0,4 mm. long by 0.16 mm. broad; its proximal por- 

 tion is very muscular and contains a vesicula seminalis. Yas deferens, 

 large and i^rominent, extends from the region of the iemale glands to the 

 cirrus pouch in the proximal portion of the segment; testicles for the 

 greater part in the distal portion of the segment, about 50 in number, 

 arranged in an irregular row across the median field. Female glands 

 first appear in the eighth to fourteenth segment alternately right and 

 left of the median line; uterus spreads from female glands and occupies 

 entire median field ; ova globular with three thin membranes ; pyriform 

 body a]>parently not present; outer membrane 40 to 42 /< in diameter; 

 middle membrane"?; inner membrane 21 /< in diameter; hooks of onco- 

 sphere 9 /< long. Calcareous corpuscles present. 



Host. — Lepus, sp. 1, by Curtice, development unknown. 



Types. — Description based upon five si^ecimens, of which Bureau of 

 Animal Industry Cestode Series No. 1171 is designated as Tyjie and 

 deposited in the United States National Museum; paratypes Nos. 1170, 

 1172, 1175, 1176 U.S.N.M. 



Original material poorly preserved, alcohol (?) method, stained with 

 hannatoxylin. 



Geo(iyapMcal distribution. — United States of North America (State?) 

 by Curtice. 



