NO. 1892. A NEW PARASITIC NEMATODE— RANSOM AND HALL. 179 



viewed from the side, the optical section of the cuticle forming the 

 ventral boundary of the swelling is usually oval but sometimes has a 

 more rectangular outline, resembling somewhat the trigger guard on 

 a rifle. The swelling is apparently filled with a clear transparent 

 iluid. The prcbursal papilla} are located near the lateral limits of 

 this swelling and about 15 /z in front of the anterior edge of the bursa. 

 ' Female (fig. 1), 8.8 to 9.8 mm. long by about 13 // -wide in the region 

 of the vulva. The head measures 20 to 25 pL in diameter. At the 

 nerve ring the body is 50 to 60 fi in thickness, at the base of the esoph- 

 agus 70 to 80 /<, and at the anus 50 to 55 /<. The esophagus is 580 

 to 020 n long and is surrounded by a nerve ring 220 to 255 /t from the 

 anterior end. The excretory pore is 265 to 320 pL from the anterior 

 end. Cervical papilla?- not evident. The vulva (fig. 4, vul.) is trans- 

 versely elongated, commonly presenting a crescentic outline with the 

 convexity of the crescent directed posteriorly. At times a very 

 small, rudimentary cuticular flap (fig. 4, lah.) is evident. The vulva 

 is situated 1 to 1.3 mm. from the posterior end of the body. The tail 

 (fig. 3) tapers posteriorly, always curving ventrally and usually 

 curving more sharply near the end to form a rather open hook, which 

 terminates in a slightly enlarged, rounded tip. The cuticle of the tail 

 beginning in the anal region and extending to the tip is marked by 

 very fine transverse striations close together. The anus is situated 

 120 to 150 /( from the tip of the tail. The cuticle surrounding the 

 anus is usually swollen so that a prominence appears at this point 

 25 to 35 fi in diameter and 5 to 8 /< high. The combined length of the 

 muscular portions of the ovijectors (fig. 4, onij.), including the sphinc- 

 ters, is 220 to 360 //. The maximum size of the eggs (from measure- 

 ments of eggs observed in the ovijectors) is 85 // long by 65 p. wide 

 (fig. 4,^.). 



Host. — Ovis aries. 



Location. — Fourth stomach. 



Localities collected. — Colorado; Montana. 



Type- specimens. — Cat. No. 16083, U.S.N.M. (Bureau of Animal 

 Industry Helminthological collection); collected July 30, 1911, at 

 Wells's ranch, Resolis, Colo., by B. H. Ransom from the fourth 

 stomach of a sheep. 



REFERENCE. 



Ransom, B. H. 1911. The nematodes parasitic in the alimentary tract of cattle, 

 sheep, and other ruminants. Bull. 127, Bureau Animal Ind., U. S. Dep. Agr., 

 Washington, 132 pp., figs. 1-152. 



