122 PAR.\SIiOLOGY. 



ed toward the opening of the mouth. The genital 

 opening in the female is found a short distance from 

 the tip of the tail. The body is thick with rather 

 abrupt narrowing at both ends. The skin is rather 

 thick with deep transverse markings. Two uteri ex- 

 tend forward from a short vagina. 



There are two species of this genus, viz : minor and 

 serratus. 



The word triodontophorus comes from the fact that 

 there are three teeth provided in the oral capsule. 



Triodontophorus minor. — The male measures up 

 to 13 mm. (one-half inch) long and about .7 mm. 

 thick while the female measures up to 14 mm. 

 (two-thirds of an inch) long and .8 mm. in thick- 

 ness. The body of the female terminates short and 

 blunt. The caudal pouch of the male is rather large. 

 This worm is found principally in the last portion of 

 the colon. See figures 24a, 25 and 26, Plate 10. 



Triodontophorus serratus. — The male measures up 

 to 18 mm. (three-fourths of an inch) long and about 

 1 mm. in thickness and the female 25 mm. (one 

 inch) long and about 1 mm. thick. See figure 

 21, Plate 10, and figures 22, 23 and 24, Plate 10. 

 The worm shown in figure 21 is taken from a throm- 

 bus of the anterior mesenteric artery of an eleven- 

 months-old colt. It is casting its last moult having 

 just arrived at the fully developed state. It is a male 

 worm. 



The Sclerostomum-Tetracanthum Group. 

 In the group of parasites commonly known under 

 the name of Sclerostomum tetracanthum will be dis- 



