98 MR. R. I. POCOCK OX THE [Ji^iie 3, 



4. On the Marine Spiders of the Genus Desis, with 

 Description of a new Species. By R. I. PococK, F.Z.S. 



[Received May 22, 1902.] 



(Text-figure 21.) 



In this paper an attempt has been made to collect what is 

 known of the habits of the marine or, more strictly speaking, 

 littoral Spiders belonging to the genus Desis. It has been im- 

 possible to give a full account of the specific characters of all the 

 known forms, since only four out of the seven described species 

 ai-e actually known to me. For the remainder I have been de- 

 pendent upon the figures and descriptions published by other 

 authors. 



I have already pointed out (Ann. Mag. Nat. Hist. (6) xvi. p. 143, 

 1895) the identity between the so-called genera Z>^s^s, Dandridfjia, 

 and Rohsonia, and Simon has subsequently and independently 

 confirmed the synonymy of Desis and liohsonia (Hist. Nat. Araign. 

 ii. p. 228, 1898). The genus Paradesis was instituted for the 

 reception of the two S. African species of the same group, which 

 differed from the species recorded up to that time from the Indo- 

 and Austro- Malayan and New Zealand seas in the wider spacing 

 of the eyes and the weak spine-armature of the legs — characters 

 which, taken in conjunction with the geographical distribution 

 of the two sets of species, appeai'ed a sufiicient basis for the 

 establishment of the genus Paradesis. 



A few months ago, however, the British Museum received from 

 Miss Kenyon a specimen of a marine spider which was discovered 

 on the coast of Victoria, in Australia. Curiously enough, this 

 spider in the spacing of its eyes approximates to the South African 

 species; and in the spine-armature of its posterior legs is also 

 moi-e nearly allied to the latter than to the kno^vn New Zealand 

 and Austro- Malayan forms. 



Since, therefore, no reasons based upon geographical grounds can 

 now be alleged in support of the genus, I propose to drop Para- 

 desis as a synonym of Desis, on the supposition that additional 

 intermediate forms between the two types will in all probability 

 be discovered in the Australian seas, and also because, so far as 

 the spine-armature of the legs is concerned, the two South African 

 species appear to difier from each other more than one of them 

 does from the new Australian species. 



Genus Desis Walck. 



Desis Walckenaer, Ins. Apt. i. p. 610 (1837). 

 Dandridgia White, Proc. Zool. Soc. 1847, p. 5. 

 Rohsonia O. P. Cambridge, Proc. Zool. Soc. 1879, p. 686. 

 Paradesis Pocock, Bull. Liverpool Mus. i. p. 75 (1898). 

 In case it may be found possible and desirable in the future to 

 resuscitate any or all of the above-given generic names, it is 



