6 PROCEEDINGS OF THE NATIONAL MUSEUM vol.75 



medio-lateral the stoutest. The externo-dorsal ray, the basal origin 

 of which could not be definitely determined, is very slender. A pair 

 of exceedingly minute prebursal papillae are also present. 



The spicules are equal in size, about 0.31 mm, in length, and brown 

 in color. Each is composed of a proximal and terminal portion. 

 The proximal portion, about 0.18 mm. long and 0.025 mm. broad, is 

 adorned with one or two, somewhat twisted, longitudinal crests or 

 ridges, and appears to be tubular in form. The distal portion is 

 filiform and flexible, often being bent, as Leiper described, in the 

 form of an interrogation mark. The tips of the spicules are not 

 united by a membrane. The genital cone lies ventral and just 

 anterior to the dorsal lobe of the bursa. It is ornamented with 

 tuberclelike papillae, but details of this structure could not be seen 

 in the material available. 



Female. — 18 to 22.0 mm. long with a maximum diameter of about 

 0.30 mm. near the middle. The terminal part of the intestine is 

 narrowed to form the rectum with cuticularized lumen which opens 

 at a point where the body is 0.12 mm. wide, about 0.37 mm. from 

 the posterior extremity. The body narrows gradually to form a 

 conical tail. The vulva is without salient lips and, in a specimen 19.3 

 mm. long, is situated 45 mm. from the posterior extremity. The 

 long uteri open through divergent muscular ovejectors into a short 

 vagina. The eggs are ellipsoidal and have thin shells which measure 

 from 66/i to 73ju long by 40m wide. 



Host. — Hippopotarmis ampMhius. 



Location. — Stomach (?). 



Locality. — Lake Albert, Central Africa, April 17, 1927. 



Specimens. — Males and females. Cat. No. 8014, U.S.N. M., Helm. 

 Coll. 



The above description is based upon material collected and pre- 

 served separately from two hippopotami. The parasites, of which 

 about 20- worms were collected from each animal, appear to be 

 identical, but the material in one tube only was in reasonably good 

 condition for study; because of the fixation the material from the 

 second animal could not be cleared to show the internal anatomy. 

 The species was first recorded and briefly described by Leiper (1910), 

 who collected it from a hippopotamus shot in the Uganda and 

 named it Nematodirus hopTceni. Leiper's description is unfortunately 

 incomplete, and the diagrams accompanying the description are 

 not accurate enough in certain details to be of service for the indenti- 

 fication of the parasite. The shape of the spicules, however, is 

 so distinctive that although the range of the present material is 

 slightly larger than shown by Leiper's figures, there can be little, 

 if any, doubt that we are concerned with the same species. Leiper 

 described the bursa of the male as being devoid of a posterior or 



