784 



ON THE CH^TOSOMATID^E 



total bocly-length. The tail is fairly long and slender, tapering 

 gradually to a fine point; and is longer in the male than in the 

 female. The body is covered by a thin, delicate, semitransparent 

 cuticle, which is marked by very delicate, transverse striations, 

 except at the two extremities, where it is quite smooth; and in 



Fig. 25. — Ch. haswelli, n.sp. 

 A. , x\nterior extremity of head of male, showing details of structure of 

 rostrum (r.), and banded area (/>.), lateral view. — B., similar view 

 of head of female, to show difference in form of lateral sense-organ 

 [Lo.) ; ( X 630) ; m.li., hairs surrounding mouth; a.h., terminal 

 hairs of the rows extending down the trunk; p., pores in the stria? 

 of banded area. 



the middle region of the head, where there are from eight to 

 fifteen much thicker ridges, forming a well marked band. The 

 head, therefore, is distinguishable into three regions, a smooth, 

 anterior end or 'rostrum' (PI. xlvi., r,); a banded area (6.); and 

 a broader region behind it, on which the transverse striations 

 are inconspicuous. The rostrum is short, about one-fifth to one- 

 sixth the total length of the head, and is blunted off in front. 

 The banded area is of about equal length, and appears to con- 

 strict the head, which broadens out considerably behind it. The 

 ridges forming this band slightly overlap one another from behind 

 forward (Fig. 25, 6.); and, in each ridge, continuing right round 

 its circumference, there is a single row of fine pores set very 



