438 CEYLON PEARL OYSTER REPORT. 



water one. An analysis of the recorded Echinoderms gives us the following 

 result : 



Crinoidea . . 10 Maldivian species, 16 Ceylon species, 5 in common 



Asteroidea . . 13 ,, 25 ,, ,, 8 ,, 



Ophiuroidea .12 ,, 13 ,, ,,5 ., 



Echinoidea . . 15 28 12 



In the Amphipoda 11 species out of the 19 found in the Maldives occur also in 

 Ceylon. Even in the Isopoda a few species, such as Oirolana sulcaticauda, Lanocira 

 gardineri, and Gymodoce inornata, are common to both faunas. Mr. Laurie considers 

 that the Ceylon crabs show a marked resemblance to those of the Maldives, over 70 

 of the species being identical. 



In some groups little relationship is shown. In the Nudibranchiata only one 

 Ceylon species extends to the Maldives ; amongst the Hydroids there are two, but in 

 addition we find several pairs of representative or closely allied species which might 

 by some be regarded as identical forms. The Maldive Cephalopoda, according to 

 Dr. Hoyle, exhibit a "remarkable likeness" to those of Ceylon, and several species 

 are identical. Mr. Browne, on the other hand, calls attention to the dissimilarity of 

 the Medusae, but we must remember that two successive collections of Medusae 

 (Gardiner's and Agassiz's) made in the Maldives were also very dissimilar. 



Confining our attention now to the Ceylon marine fauna, we may conveniently 

 divide our records into three sets of localities : 



1. Trincomalee and the north-east coast (Stations XX. to XXXI.*). 



2. Galle and the south end of the island up to Colombo (Stations XXXII. to XL VI.). 



3. The Gulf of Manaar and around Adam's Bridge, from Colombo to Palk Bay 

 (Stations I. to XIX. and XL VII. to LXIX). 



Of these three regions of the coast, the first two have deeper water and a more 

 varied fauna than is found in the pearl-bank region of the Gulf of Manaar. But, on 

 the other hand, we have more stations in the third district, where much more time was 

 spent and where the fauna, on the pearl banks, was consequently studied much more 

 closely than elsewhere. The following table gives the number of species in each group 

 of animals found in each of the three districts : 



* See "Narrative," in Part I. (1903), for details as to the Stations. 



