800 



ON THE CH^TOSOMATID^, 



covering it is very thick, and has a serrated anterior marpjin. 

 Beyond it, is a projection of tissue, 0*01 1 mm. long, with .a 

 rounded extremity, in the middle of which the very small, circular 

 mouth-opening (Fig.48, ??i.) is situated. The width of the body, 

 just behind tlie rostrum, is 0-040 to 0*050 mm., which decreases, 

 at the level of the neck-curve, to a width of 0*033 to 0*037 nun. 

 The length of this anterior, ventrally curved portion varies, in 

 different individuals, from 0*122 to 0*150 mm. Behind it, the 

 body gradually increases to a widtli, in the male, of 0*050 to 

 0"060mm., and, in the female, in tlie region of the genital organs, 

 of 0*070 to 0*096 mm. 



Fig. 48. — Xofochnfo-soma fenax, n.sp. 

 Lateral view of anterior extremity; ( x 630). 



The tail (Fig.49, tl.) is narrow, and sharply pointed. In the 

 male, it averages 0*085 mm. from anus to tip; in the female, 

 0*077 mm. Cuticular striations are absent from the terminal 

 portion (0*040 mm. long), and the anterior half of this part is 

 closely pitted. A pair of long hairs is inserted on its dcn-sal 

 surface, just at its junction with the striated area (Fig.49, r.h.). 

 As in the other species, the anus is situated on the mid-ventral 

 surface, close to the posterior end (Fig.49, a). The ventral setw 

 are arranged in four rows, and cover a length of about one-sixth 



