TO INDIAN CAECINOLOGY. 333 



of a large number of the marine species — which from time to time are discovered 

 in widely separate localities — is appai-ently to a great extent determined by the dis- 

 tribution of coral reefs, and as regards the higher Crustacea, at least, any attempt to 

 subdivide the large central or coral-reef region of the Indo-Pacific area seems of doubtful 

 value, and we can scarcely seek for natural subdivisions till we pass into the temperate 

 and colder waters, north and south of the coral region. Nearly two thirds of the total 

 number of species recorded in this paper are known to occur in the seas of the Malay 

 Archipelago ; about one third occur at Mauritius or the neighbouring islands ; the same 

 proportion in the seas of North Australia, and a slightly greater number in the islands 

 of the Pacific (New Caledonia, Pijis, Samoa, Sandwich Is., &c). Nearly one fortrth of 

 the number occur at Japan ; while one fifth are found in the Red Sea, the same pro- 

 portion on the east coast of Africa, and about the same in Australian localities excluding 

 those on the north coast. Not less than twenty-seven of our species occur on the 

 coast of Natal, and at least thirteen in the seas of New Zealand ; while eight extend 

 their range into the Atlantic area. The same amount of attention has not been paid by 

 collectors to each of these regions, some having been more specially favoured ; but, in 

 spite of this, there can be no doubt of the great affinity between the Indian and Malayan 

 Crustacean faunas. 



The distribution of the freshwater species offers certain points of interest. The genus 

 Tel/phusa has representatives in South-Eastern Asia (Malay Archipelago, Malay Peninsula, 

 and China) of what may be termed a granulated group of species ; in Burmah and Upper 

 India similar forms are met with, e. g. T. Atkinsonianu, Wood-Mason, and T. Pealicma, 

 Wood-Mason, which so far as is known do not extend their range into the Indian 

 Peninsula*; while further west, in Beloochistan and Persia, the allied T. ftaviatilis 

 makes its appearance, and finally spreads along both sides of the Mediterranean. The 

 genus Paratelpliasa has a somewhat similar range, extending from the Malay Archi- 

 pelago along the Malay Peninsula into Burmah and Northern India, but no species 

 have yet been recorded from South India or Ceylon. Very little is as yet known 

 of the Indian species of Palcemon, but there can be no doubt that they are very 

 numerous. P. scabr'tcidus, a very well-marked species, described originally from Ceylon, 

 occurs in Upper India and in the Malay Archipelago ; it, however, remains to be seen 

 whether it does not also occur in Burmah and the Malay Peninsula. The marked 

 prevalence of freshwater prawns in the streams of South-eastern Asia and the Malay 

 Archipelago, v ith the apparently complete absence of crayfish from the same region, 

 seems to strengthen Professor Huxley's suggestion that the latter have been displaced 

 by better fitted competitors. The genus Garidina is represented at Madras, and 

 probably elsewhere in India, by a species which 1 am unable to separate from 

 C. Wyckii, described by Hickson from Celebes, and which itself is perhaps not distinct 

 from a longer-known species, found in North and East Africa, a remarkably extended 

 range for a fresh-water species. 



* In the British iluseum there is a specimen of T. Athinsoniana from Ceylon. 

 SECOND SERIES. — ZOOLOGY, VOL. V. 49 



