BY VERA A. mWlN-SMlTH. 785 



close together (Fig.25, />.). The pores are very deeply embedded 

 (Fig. '30, p.), but show, on the surface, as a row of fine, bright 

 dots. They appear to be present only in this region, though the 

 surface of the rostrum also is very finely, but irregularly, pitted 

 all over. 



The lateral, spiral grooves on the rostrum are large and con- 

 spicuous; the spiral is simple and very open, and is turned away 

 from the dorsal hairs in the female, and towards them in the 

 male (Fig. 25, l.o.). Embedded in the hypodermis, below the 

 groove on each side, is a peculiar cell, probably sensory in char- 

 acter (Fig. 31, x), which may have some relation to these lateral 

 organs, though I cannot trace any direct connection between 

 them. The dorsal semicircle of stout 'head-hairs' or set?e, in the 

 adult, consists of five or six pairs arranged in two rows close to 

 the posterior margin of the rostrum (Fig. 25, d.s.), the seta? of the 

 posterior row being wedged against the most anterior of the 

 ridges of the banded area. They have an average length of 

 0*025 mm. All the setae are bent forward to such a degree, that 

 they lie close to the surface of the rostrum, and follow its shape. 

 They are enlarged at the base, and are long enough to project 

 over the anterior end, where there is a lip-like arrangement 

 surrounding the mouth (Fig. 25, 7n.). 



One immature female, without a genital pore, was found, in 

 which there were only four sette in a single row (PI. xlvii., 6.). 

 In this case, the two inner setie were inserted very close together 

 in the dorsal mid-line; and the outer ones, separated from them 

 by a fairly wide interval, are just dorsal to the spiral groove on 

 each side. Close to the outer side of each seta is a long, fine 

 hair. 



The ventral setie (PI. xlvi., i.r., o.r.) are confined to a small 

 portion of the trunk, usually about one-seventh the total length 

 of the body, whether this is O'GO or 1*44 mm. The sette are 

 arranged in four rows, beginning some little distance in front of 

 the anus, about 0'051 mm., in mature worms of both sexes, and 

 0"034 mm., in young worms. 



The two inner rows are situated very close together, and con- 



