DESCRIPTIONS OF GENERA AND SPECIES 



553 



(4) Oetochaetus antarcticus (Beddaed). 



Acanthodrilus antarcticus, Beddabd, P. Z. S., 1889, p. 378. 

 O. antarcticus, Beddaed, ibid., 1892, p. 669. 



Definition. Length, 240 w.m.; breadth {at diteUum), 7 mm.; number of segments, 176. 

 CliteUum, XII-XVII. Setae in couples, not closely apj.roximated. The two setae of 

 each ventral couple rather closer together than those of the dorsal couples. At the posterior 

 end of the body the setae are longer and more prominent than anteriorly, being borne upon 

 more distinctly marked papillae. Dorsal pores commence V/VI. Gizzard in VI; 

 calciferous glands in XV, XVP; in XYII the very narrow oesophagus suddenly widens 

 out into the intestine. First septum in front of gizzard ; like the one which immediately 

 follows the gizzard it is thin and transparent. The six next septa {the last of which bounds 

 the twelfth segment posteriorly) are thick and muscular. Dorsal vessel completely double ; 

 four pairs of dilated hearts in X-XIII. Gonads all attached to front wall of their 

 segment. In addition to racemose sperm-sacs of other species this has two pairs of 

 tongue-shaped sacs in IX and X. Penial setae present, with very faintly marked ornate 

 ridges at tip. Spermathecae, two pairs {in Fill, IX) with three or four small diver- 

 ticula clustered round the duct. Hab. — New Zealand. 



The penial setae are very small as compared, for example, with those of Acantho- 

 drilus disdmilis, but they are more decidedly and for a longer tract ornamented 

 than I have indicated in Q. J. M. S., vol. xxx, PI. xxx, fig. 17. 



Genus Kerbia, Beddaed. 



Di!Fii9'iTio]!9'. Setae paired, present on all the segments of the body except seta 

 2 on segments XVII, XIX of some species. No dorsal pores. Nephridia 

 paired. One pair of testes in X. Spermiducal glands lined by a single layer 

 of cells ; no penial setae. Spermathecae with or without diverticula. 



This genus consists of four species. The first of these was described some three 

 years since by Rosa (6)) who regarded it merely as a species of the genus Acantho- 

 drilus. It is evident, however, from his account of the structure of this ' Acanthodrilus ' 

 that it shows characters not found in other specimens of the genus Acanthodrilus then 

 known or since discovered. In the first place the spermathecae, although occupying 



' In the fourteenth segment the oesophagus is swollen, and has very thick folded walls ; perhaps this may 

 be counted an anterior gland ; the diameter is, however, considerably less than in the two next segments. 



4B 



