2 PROCEEDINGS OF THE NATIONAL MUSEUM Vol. 71 



dentation is present which divides it into two smaller lobes which 

 are supported by the two dorsal rays. These rays are bifurcated 

 near the tip, the lateral branch being slightly longer than the median. 

 The externo-dorsai rays are quite widely separated from the other 

 rays, slender and curved slightly dorsad. The postero-lateral and 

 medio-lateral rays are long, slender, and parallel except near their 

 tips where they diverge slightly and terminate near the edge of the 

 bursa. The externo-lateral ray arises from the same common stem 

 wdth the medio-lateral and postero-lateral rays; it runs parallel to 

 the medio-lateral ray for about one-half of its length and then bends 

 ventrad at almost a right angle. The ventral rays diverge slightly 

 near their tips and terminate near the edge of the bursa. Bursal 

 maculae or bosses appear to be absent. The spicules are long and 

 measure 4.1 to 4.4 mm. They are united for the greater part of 

 their length. The tip is straight and semilanceolate. (Fig. 3.) 



Female 24 to 29 mm. long and with a maximum thickness at the 

 vulva of about 250/j, to 350/i,. The body thickness is noticeably reduced 

 immediately behind the vulva. The tip of the tail is truncate and 

 bears an acutely pointed bristlelike process 14fi in length. (Fig. 4.) 

 The anus is located 100/x to 115 fj. from the truncate tip of the tail. 

 The vulva is a transverse slit situated about 1 mm. anterior to the 

 middle of the body. The ovejectors are long, the combined length 

 being about 4 mm. The posterior ovejector measures about 2.5 mm. 

 and the anterior about 1.5 mm. in length. The anterior uterus is 

 atrophied and appears to be sterile. The eggs are oval, with shells 

 of uniform thickness, and measure 240,u long and 130/i, wide. 



Host. — ui 7itiIocaprci a mericon a . 



Location. — Small intestine. 



Locality collected. — National Zoological Park, Washington, D. C. 



Tjjpe spechneiis. — United States National jSIuseum Helminthologi- 

 cal Collections No. 27438. 



This species belongs in the N. 'mauritanicus group as described by 

 May (1920). It is quite similar to N. m-aurltanic^is, which was de- 

 scribed by Maupas and Seurat (1912) from the dromedary, but 

 differs from this species in location of vulva and position of uteri. 

 In N. mamitanicvj^ the vulva is located about 4 mm. posterior to the 

 middle of the body and both uteri are directed backward, while in 

 N. antilocaprae the vulva is about 1 mm. anterior to the middle of 

 the body and one uterus lies in the anterior and the other in the 

 posterior part of the body. Maupas and Seurat do not state whether 

 both uteri in their species are functional or not. Their figure, how- 

 ever, suggests that possibly one may be sterile. The atrophied con- 

 dition of the anterior uterus in N. antilocaprae relates it to N. 



