INTRODUCTION. 15 



Tennent's ' Ceylon ' (1 859) there is a good summary of the fauna as known up to 

 that time, with lists which were supplied, or supplemented, or revised by HUXLEY, 

 Gray, Hanley, Kelaart, and others. Further papers on new animals in various 

 groups (many of them collected by Dr. W. C. Ondaatje) have been published from time 

 to time by Bowerbank, Allman, Ridley, Dendy, Bell, Carter, Nevill, and the 

 Sarasins. But the most notable contribution to our knowledge of the marine fauna 

 is Thurston's ' Notes on the Pearl and Chank Fisheries and Marine. Fauna of the 

 Gulf of Manaar,' published from the Government Central Museum, Madras, in 1 8'JO. 

 In this interesting little work Mr. E. Thurston, with the help of Professor Dendy, 

 Professor Jeffrey Bell, Professor Henderson, and Mr. E. A. Smith, gives con- 

 siderable lists of the Porifera, Ccelenterata, Echinodermata, Crustacea, Mollusca and 

 Pisces which he had collected during visits to Tuticorin, Rameswaram, and some parts 

 of the Ceylon pearl banks. 



Taking a somewhat wider area the northern part of the Indian Ocean there are 

 three recent series of faunistic explorations which have some bearing on oiir work, 

 viz., the reports upon Dr. Anderson's collections made in the Mergui Archipelago 

 ('Journal Linnean Soc, Zool.,' vols. XXI. and XXII.), the great series of Memoirs, 

 Reports, and ' Illustrations ' issued by Major Alcock, of the Calcutta Museum, as 

 a result of the explorations of the surveying vessel " Investigator," and lastly, 

 Mr. Stanley Gardiner's series dealing with ' The Fauna and Geography of the 

 Maldive and Laccadive Ai'chipelagoes ' (Cambridge Press). The Ceylon marine fauna 

 resembles that of Mergui in some respects, but differs in detail ; Dr. Alcock's 

 " Investigator " work has been mainly though not wholly in the abyssal waters 

 of the Indian seas ; while the Maldives are an Oceanic group, in contrast to Ceylon 

 which is faunistically as well as geologically a part of India. Our dredgings were 

 nearly all within the 100-fathom line, and were mainly in the zone of 5 to 20 fathoms. 

 This account of a shallow- water Continental coast fauna may till a gap and be of use 

 for comparison with these other recent investigations in the Indian Ocean. 



The faunistic reports which will appear along with this Introduction in Part I. 

 will tell their own story, but it may be well to give briefly what information I can in 

 regard to a few of the other groups, the reports upon which may not be ready for 

 some months. 



Professor Dendy has sent me a preliminary report upon the Sponges as follows : 

 " This collection of sponges appears to be by far the most extensive that has ever 

 been made in Ceylon waters, and contains many species of great interest. Amongst 

 the siliceous sponges, the Tetractinellida are represented by at least a dozen species, 

 including a new Stelletta, a new Plakinastrella, and a form which will be described 

 as the type of a new genus under the name Dercitopsis cingalmsis. There are also a 

 massive Lithistid, a Placospongia, and a curious Suberites-like species which is 

 anchored by silky tufts of spicules in soft mud. Amongst the Monaxonids, the 

 Chalinidse, Ectyoninaj, and Axinellidse are the most conspicuous groups ; while of 



