DESCRIPTIONS OF GENERA AND SPECIES 663 



Genus Diachaeta, Benham. 



Syn. Fontoscolex, Schmaeda (in part.). 



Defiititiow. Frostomium absent ; setae irregular from the first. Mucous gland 

 present. Calciferous glands absent. Sperm-sacs very long. Spermathecae two 

 or three pairs. Testes and funnels, one pair. 



This genus is very near to Fontoscolex and to Onychochaeta. It differs from 

 the former chiefly in the facts that the setae are irregular from the first, and that 

 there are no glands connected with the posterior nephridia. Our knowledge of 

 the genus is chiefly derived from Benham's description of D. thomasii; my own 

 notes upon a second species are not so full. I found, however, that the setae are 

 occasionally bifid, a point not referred to by Benham ; this brings the genus 

 into somewhat nearer proximity to Fontoscolex, as does also the fact that the 

 end of the nephridia is surrounded by the cup-shaped body so characteristic of 

 Fontoscolex. As will be seen in the following lines, there is no possibility of 

 confusing the two species of the genus. 



(i) Diachaeta thomasii, Benham. 

 D. Thomasii, Benham, Q. J. M. S., vol. xxvii, 1887, p. 89. 



Definition. Length, about 3 inches; diameter, about \ inch; number of segments, 335. 

 Clitellum, XX-XXXIII, complete. Septa VI/XI very much thickened. Gizzard in VI; 

 intestine begins in XL Last heart in XL Sperm-sacs extend from XLI-XXXVLLL, 

 constricted at the septa. Spermathecae in VL, VLI, VIII. Hob. — St. Thomas, W. L. 



The specimens examined by Benham were so much contracted that the above 

 measurements are probably incorrect. 



(a) Diachaeta littoralis, Beddakd. 



Fontoscolex arenicola, ScHMAEDA, Neue wirbell. Thiere, I, ii, 1861, p. a (in part.). 

 D. littoralis, Beddaed, Ann. and Mag. Nat. Hist., Feb. 189a, p. ia8. 



Definition. Length, ^ or 4 inches. Setae not ornamented, but bifid; clitellar setae longer 

 and ornamented. Clitellum, XVI-XXXI. Spermathecae, two pairs. Hab.— Jamaica ; 

 sea-shore. 



