NO. 2131 



NEMATODE PARASITES OF RODENTS— HALL. 



127 



tero-lateral and medio-lateral rays of about equal thickness, the Litter 

 slightly the thicker, less than half as thick as the externo-lateral ray, 

 closely approximated, except at their tips, where they diverge 

 slightly, the postero-lateral ray dorsad and the medio-lateral ven- 

 trad. Medio-lateral ray closely approximated to the latero-ventral 

 ray. Dorsal ray united at its base with the base of the right externo- 

 dorsal ray; bifurcated distally (fig. 153). The dorsal lobe of the 

 bursa is not distinct from the lateral lobes, and is deeply emarginate 

 between the distal branches of the dorsal ray. Distal branches of 

 the dorsal ray are very slender, with simple unbranched tips. Spic- 

 ules 175 to 190 fx long, nearly equal 

 in length but somewhat different in 

 shape, dark brown in color, slightly 

 curved ventrad, with truncate tips 

 and without the ventral angular 

 projection typical of TricJiostrongy- 

 lus (fig. 154). Tip of left spicule 

 with a large beaklike process or 

 spur projecting ventrally, and a 

 small spur projecting dorsally. An- 

 terior of the ventral beak a small 

 hook, and in front of the latter a 

 series of two or three small projec- 

 tions, the ventral surface of the 

 distal portion of the spicules for a 

 distance of about 50 [;, thus having 

 a hooked, barbed, and roughened 

 appearance. The ventral surface of 

 the right spicule is smooth. Tip of 

 the right spicule smaller than that 

 of the left, with a small flattened 

 caplike enlargement projecting dor- 

 sally and ventrally as very small 

 pointed processes, and laterally as a very small ridge. Gubernaculum 

 about 100 by 35 ix in length and breadth, respectively, similar in 

 color to the spicules, with an oval body and a short pointed process 

 posteriorly and a longer process anteriorly. 



Female 5.8 to 7 mm. long by 90 to 120 (i in diameter at the vulva. 

 Anus 65 to 90 /a from the tip of the tail (fig. 155). Posterior end of 

 the body is commonly rather abruptly though slightly diminished 

 in size a short distance in front of the anus, then tapers gradually to 

 the tip of the tail ; or, beginning some distance in front of the anus, 

 may taper gradually to the tip. Tail straight. Vulva 850 /x to 1 mm. 

 from the tip of the tail, elongated diagonally, 50 to 60 fx. long, with 

 inconspicuous lips (fig. 156). Combined length of muscular portion 



lOOyU. 



Fig. 154— Trichostrongylus calcaratus. 

 Spicules and gubernaculum. After 

 Ransom, 1911. guh., Gubernaculum; I. 



Sp., LEFT spicule; T. sp., RIGHT SPICULE. 



