1902.] ox A NEW MARINE SPIDER. 389 



Oeriagriox ekubescens Selys, 



Ceriagrion eruhescens Kriiger, Stett. ent. Zeit. 1898, p. 127. 



Ceriagrion coromandelianioni, race erubescens Selys, Ann. Mus. 

 Gen. (2) X. 1890. 



3 c? , 1 $ from Kliota Baru, Kelantan. Recorded from 

 Sumatra and Burmah. 



5. On a new Species of Marine Spider of the Grenns Des'is 

 from Zanzibar. By K I. Pocock, F.Z.S. 



[Received November 18, 1902.J 

 (Text-figure 78.) 



In a monograph of the marine Spiders of the genus Desis, pub- 

 lished in the Society's 'Proceedings' for 1902, vol. ii. pp. 98-106, 

 I drew attention to the fact that, so far as was then t:nown, these 

 Spiders existed only upon the coasts of Cape Colony and of the 

 countries of Austro- Malaya, and commented upon the absence of 

 any record of their occurrence along the miles of coast-line that 

 intervene between Durban and Singapore. 



While this paper was in the press I received from Mr. Cyril 

 Crossland the news that he had discovered a Spider beneath 

 stones between tide-marks while hunting for other marine objects 

 at Zanzibar. It was with great satisfaction that I undertook to 

 determine the Spiders from this new and interesting locality, 

 naturally expecting them to show close affinity to the two known 

 forms from Cape Colony. Much to my astonishment, they proved 

 to be nearly related to the species of the Austro- Malayan type, 

 not even tending in any respect to bridge over the structural 

 interval that separates the S. African from the Malaysian species. 



In the paper already referred to, I pointed out that the inter ■ 

 mediate form between the two groups of species, namely, the 

 Faradesis-grou^ from Cape Colony and the />esis-group, in 

 the strict sense of the word, from Austro- Malaya, is represented 

 in Australia by Besis kenyonce ; and this fact I suggested furnished 

 evidence in favour of the view that S. Africa had received its 

 representatives of marine Spiders from Australia by means of a 

 trans-oceanic land-connection to the south of the Indian Ocean. 

 This conclusion is in no sense invalidated by Mr. Crossland's 

 discovery of the genus at Zanzibar, because, as already stated, 

 the Zanzibar form stands no nearer to the South- African forms 

 in specific structural features than do those inhabiting the 

 Malaysian seas. The discovery shows conclusively, however, that 

 the North-eastern coast of Africa has received its representatives 

 of Desis from the same source whence the Austro-Malayan forms 

 emanated, and renders almost certain the existence of the genus 

 in suitable localities along the shores of Southern Asia westwards 

 of Singapore. 



