BY N. A. COBB. 



461 



breadth four-ninths as great as its length, this latter being twice 

 as great as the width of the body. The reflexed ovary joins the 

 uterus at a point as far in front of the vulva as the anus is 

 behind it, and extends thence backwards, past the vulva, appar- 

 ently to near the anus. The anterior half of the tail is concave- 

 conoid, the diameter of the posterior cylindrical half being only 

 one-fifth as great as the anal diameter. The terminus is distinctly 

 swollen, and gives exit to the secretion of the rather small caudal 

 glands. 



3-53. mm. ^hc tail of the jnale is like that of the 



16 7-5 16-9 -a-*" 9*S 



1-2 1-8 2- 21 



female. The two narrowly linear, nearly straight, equal spicula, 

 one-third as long as the tail, are almost imperceptibly arcuate in 

 the distal half. Seen in profile, they appear to lie at an angle of 

 30° with the axis of the body. Their proxirase are not sufiiciently 

 contrasted with the shafts to be distinct. The two equal testicles 

 occupy the middle half of the body. About ten hairs stand 

 opposite the distal half of the spicula. 



Hah. — This species is common on the coasts of the Northern 

 Indian Ocean. I found it abundant in sand and among algse on 

 the coasts of Arabia, Ceylon, &c. Individuals of both sexes 

 were mature in February. 



O. ANGUSTATUS, Cobb*. -g "^ i-g ^ Vg 1-77 mm. Nor IS thlS 



species striated. The only conspicuous setse are the six short 

 ones which surround the head opposite the apex of the longest 

 pharyngeal tooth. The anterior half of the neck is convex-conoid. 

 The head is slightly constricted just behind the seise, and this 

 gives rise to a comparatively distinct labial region. Circular 

 lateral organs probably exist opposite the base of the pharynx. 

 This latter is nearly as wide as deep and bears three teeth, two of 

 them only half as long as the third (the right submedian), which 

 reaches nearly to the six lamelliform lips. These latter are of the 

 form described for the preceding species. The oesophagus is two 

 thirds as wide as the neck and presents at its posterior extremity a 

 rather indistinct cardiac collum. The narrow duct of the ventral 



* Cobb, " The Dififerentiator. " Sydney, 1889. 



