388 Annals of the South African Museum. 



distant 8 miles (Zululaud). 55 fathoms. 1 <$ . s.s. " Pieter Faure."" 

 11/10/00 and 28/2/01. (S.A.M. Nos. A3862 aiid A4129.) 



This species is named after the extraordinarily slender form of 

 the male. I see no reason to doubt that the male and female are 

 couspecific. 



The structure of the marsupial plate on the 4th segment is quite 

 different from that of A. longicornis, deshayesii or mediterranea as. 

 figured by Koehler. 



ASTACILLA MEDITERRANEA Koehler. 



1911. Astacilla mediterranea Koehler, I.e., p. 44, figs. 25-29. 



The single female agrees so well with Koehler 1 s description that 

 I think there can be no doubt as to the specific identity. In one or 

 two details there is a slight difference, and in one point a comparison 

 is not possible because Koehler does not mention it. A future 

 comparison of South African specimens with the types may therefore 

 possibly lead to the former being separated as a variety, though 

 scarcely I think as a new species. 



In the first place there are scarcely any setules developed on the 

 tubercles, in which connection see the remarks on the variability of 

 a similar feature in Arcturella corniger infra. The tubercles on the 

 head and 1st peraeon segment curve gently forwards. The tubercle 

 on the 3rd peraeon segment is much smaller than in Koehler's figure,. 

 and there is in addition a similar, though even smaller, tubercle on 

 the 2nd segment ; both these tubercles curve backwards and are 

 merely the slightly more developed forms of the granules or 

 " squamules " which are distributed generally over the whole surface. 



The median tubercle on the 4th segment is not symmetrical in 

 profile as in Koehler's figure, but has a more gradual anterior, a, 

 steeper and more abrupt posterior, slope. Of the posterior median 

 tubercle (anterior to the one on the posterior margin) only one is 

 developed, and that immediately in front of and almost contiguous 

 with the large one on the posterior margin. On either side of this 

 latter tubercle, i. e. ou the upper postero-lateral angles of the segment,. 

 is a small conical process which may correspond with that which 

 Koehler describes as on the inferior angle. 



Secondly, the point on which Koehler is silent : the lateral margin 

 of the 4th segment is slightly turned out horizontally instead of 

 continuing in the same plane as the rest of the segment, forming a 

 very shallow groove which is quite smooth and free from granules. 

 On the margin itself, however, is a very regular row of granules, and 



