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Show C er ia g r io n er u b esc ens Selys. Cerictgrion erubescens Kriiger, Stett. ent. Zeit. 1898, p. 127. Ceriagrion coromandelianum, race erubescens Selys, Ann. Mus. Gen. (2) x. 1890. 3 c?, 1 ? from Khota Baru, Kelantan. Recorded from Sumatra and Burmah. 1 9 0 2 .] OX A NEW MARINE SPIDER. 389 5. On a new Species of Marine Spider of the Genus Desis from Zanzibar. By II. I. P o c o c k , F.Z.S. [Received November 18, 1902.J (Text-figure 78.) In a monograph of the marine Spiders of the genus Desis, published in the Society's ‘ Proceedings' for 1902, vol. ii. pp. 98-106, I drew attention to the fact that, so far as was then known, 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 intermediate form between the two groups of species, namely, the Paradesis-group from Cape Colony and the Ztests-group, in the strict sense of the word, from Austro-Malaya, is represented in Australia by Desis 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. |