10 PROCEEDINGS OF THE NATIONAL MUSEUM vol.75 



while the mediolateral and posterolateral rays are parallel, and 

 extend to the margin of the bursa. The externodorsal rays, which 

 are relatively slender, arise from a common trunk with the dorsal 

 ray. The latter divides near its middle, and each branch bifurcates 

 terminally. Spicules equal in length, filiform and unsheathed. They 

 measure 1.23 mm. in length, and their termini are without barbs. A 

 slender, curved gubernaculum, about 0.10 mm. long, is present. 



Female. — From 30 to 31 mm. in length, with maximum breadth in 

 the posterior half of the body of 0.78 mm. Esophagus 0.78 mm. 

 long. Measurements of buccal cavity approximate those of the 

 male. The posterior half of the body tapers conically, to terminate 

 in a sharp mucronate tail. Anus opens about 0.15 mm. from tip of 

 the tail, and the vulva, which does not have salient lips, is situated 

 about an equal distance anterior to the anus. Muscular vagina 

 about 0.28 mm. long. It bifurcates into two more or less kidney- 

 shaped chambers, that receive two convergent ovejectors, which are 

 continuous with the parallel uteri. Eggs (in uterus) thin shelled, 

 measuring, on the average, 80m by 40ai. 



Host. — Colohus polyJcomos ("Black and white" Colobus monkey). 



Location. — Small intestine (?). 



Locality. — Du River, Liberia. 



Type.—M&\e and female. Cat. No. 8017, U.S.N.M., Helm. Coll. 



Paratypes. —C&t. No. 8018, U.S.N.M., Helm. Coll. 



Nine female and seven male specimens of the parasite described 

 above were found free in the lumen of the small intestine of the host, 

 which, at the time of examination, had been dead for several hours. 

 Cysts, the size of a pea, resembling those produced by Oesophagostomum 

 were seen by Dr. Max Theiler, a member of the expedition, on the 

 walls of the cecum, but on dissection of one of these cysts no para- 

 sites were found. Because of the generic affinities of the worms, it 

 seems not unlikely that the normal habitat of the parasite is in the 

 large intestine and that, in the present case, post-mortem migration 

 had occurred. 



The characters described in the diagnosis can not be reconciled 

 with those of any known genus of the Strongyloidea. On the basis of 

 the shape of the buccal cavity and the associated oral structures, the 

 status of the parasite would seem to fall between the two chief sub- 

 families, the Strongylinae and the Trichoneminae, but in other 

 characteristics it exhibits affinities with the Oesphagostominae. 

 The shape of the buccal cavity is closer to that of the Strongylinae, 

 but the absence of a dorsal esophageal gland prolonged as a ridge on 

 the dorsal wall of the buccal capsule is more characteristic of the 

 Trichoneminae. If it were not for the lack of a transverse ventral 

 cervical groove and of any semblance of cephalic inflations, an affinity 

 with the Oesophagostominae would be indicated, especially since the 



