770 



ON THE CH^TOSOMATID^ 



Tnimediately behind the 'head,' the trunk is sharply con- 

 stricted to form a narrow 'neck' which is less than one-third the 

 width of the head (PI. xliv.-xlv., nk.). Behind the neck, the trunk 

 rapidly broadens to its widest part in the anterior region of the 

 body, becoming slightly narrower again in the posterior region, 

 which bears the locomotor rods. The terminal portion of the 

 trunk, ''distinguished as the 'tail," is very short in this species, 



being not more than 0*05 1 mm. 

 long in the largest individuals. 

 While devoid of striae, its cuticle 

 is not quite smooth, being min- 

 utely pitted all over (PI. xlv., fig. 



c.^.-^^% 



'2a: Text-fig. 3, tL). A few, very 

 fine hairs are scattered over the 

 surface of the trunk (PI. xlv., t.h.). 

 These are never more than 0-007 

 mm. long, except towards the pos- 

 terior end, where three or four 

 pairs of much longer hairs occur 

 on the dorsal surface. The last 

 and longest of these, 0-026 mm 

 long, are inserted very close to- 

 gether just at the junction of the 

 striated trunk-region with the tail 

 (Text-tig. 3; PI. xliv., xlv., e.h.). 

 The ventral rows of locomotor seta? 

 extend from behind the anus 

 nearly half-way up the trunk, to 

 the beginning of the anterior 

 curve. The number of setae in 

 each row varies with the size and 

 but the relative extent of ventral surface 

 covered by them remains about the same in specimens varying 

 in length from 0-528 mm. (the smallest) to 1 -104 mm. (the largest 

 obtained by me), 'i'he two inner of the four rows are situated 

 close together along the middle of the ventral surface, each row- 

 consisting of from 12 setse in the smaller to 23 in the larger 



Fig. 3. — Oh. fa/cafn/n. 

 Posterior end of male; ( x o'iO). 



age of the anima 



1 



