434 



CEYLON PEARL OYSTER REPORT. 



Ceylon list and about 900 to that of the Indian Ocean. Such information, although, 

 perhaps, as uninteresting as the description of new species, is of real importance in 

 science, as it is impossible to draw conclusions as to geographical distribution, and the 

 origin and past history of faunas, until we have a detailed knowledge of the animals 

 now present in many different localities. 



In comparing with other seas, we find that about 250 of our species* extend into the 

 Malay region and 300 on into the Pacific. At least 240 are known from the Red Sea and 

 130 from the Mediterranean. About 280 species extend southwards to the Australian 

 coasts, and a few are found elsewhere in southern latitudes. Finally, 90 Ceylon 

 species are found also in the West Indian region, and may indicate a closer connection 

 by sea in a former period than exists at the present day. This interesting relation 

 between these two far-distant regions the East and the West Indies has been pointed 

 out by several writers, and in 1S99, AlcockI published an interesting chart (after 

 E. Koken) showing a direct connection by means of a great inland basin stretching 

 east and west from the Gulf of Mexico to the Arabian Sea. This indicated the 

 supposed relations of land and water in Tertiary times, and was put forward by 

 Dr. Alcock to elucidate the theory he advanced as to the origin of a considerable 

 part of the Fish fauna of India from a Tertiary extended Mediterranean stretching 

 across the present mid-Atlantic to the West Indies. 



Fig. 1. Map to show the equatorial seas and the relative positions of : I. Gulf of Manaar, 

 II. Mergui Archipelago, and III. the Maldives. 



Restricting our attention now to the northern part of the Indian Ocean, there are 

 three recent series of fauuistic explorations with which we may compare our results, 

 viz., (1) the Reports on the Mergui Archipelago, off the coast of Lower Burma (see 



* Possibly a good many more. These numbers are all minimum estimates. 



t Descriptive Catalogue of Indian Deep Sea Fishes in the Indian Museum, Calcutta. 



