A. H. CLARK : THE CRINOIDS OF THE INDIAN OCEAN. 23 



maximum depth attained is 140 fathoms. As with the preceding families, the 

 lai'ge or remarkable species are confined to the region between Australia and the 

 Philippine Islands. 



The family Tropiometridte includes but a single genus, Tropiornetra, which 

 itself contains only four species, three very closely related and one very distinct, 

 much larger than the others (T. afra). This larger species occurs from Queens- 

 land to Japan, reaching a depth of 50 fathoms ; the other species range from the 

 South Sea Islands and China to East Africa where they are found from Suez to 

 the Cape, and from West Africa to Brazil, the West Indies, and Venezuela, 

 Although the genus is almost everywhere confined to very shallow water, in the 

 Lesser Antilles the local species {T. picta) is only found at very considerable 

 depths, and, as the same is true of another widely different littoral species in the 

 same region {Nemaster lineata), we seem to have here evidence suggesting that 

 those islands have gradually subsided, carrying down these two littoral forms to 

 a level which, though once the coast line, is now more than 100 fathoms beneath 

 the surface. 



Calometridce. 



The family Calometridte is exclusively confined to the East Indian region, the 

 species occurring from the Andaman to the Ki and Philippine Islands, and thence 

 northward to Japan ; the bathymetric range is from 20 to 240 fathoms so that, 

 while not littoral, the family occurs only at moderate depths, the average being 

 about 95 fathoms. One of the genera is only known from southern Japan in 

 107 — 1 39 fathoms (C'afojwefra); another only from the Ki and Philippine Islands in 

 140 — 240 fathoms {Gephyrometra) ; a third from Jajian and the Philippine Islands 

 in 53 — 160 fathoms {Pectitwmetra) ; a fourth from the Andaman and Philippine 

 Islands and Japan in 20 — 110 fathoms [Neometra) ; while the habitat of the fifth is 

 quite unknown. The first known species was described in 1888, and all of the 

 others have been described within the last three years. 



Thalassom elridce . 



The family Thalassometridae occurs from the Bay of Biscay and the Carib- 

 bean Sea to the islands south of Africa, and from the east coast of Africa through- 

 out the Indian and Pacific Oceans, reaching southern Australia and the Galapagos 

 Islands, Hawaii, and the western Aleutian Islands. Within the East Indian 

 area it includes 54 species distributed in nine genera, and ranges bathymetrically 

 from the shore line down to 1,600 fathoms. 



The genus Thalassometra includes, in the East Indian region, 17 species occur- 

 ring in water of from 30 to 1,600 fathoms, being most abundantly represented 

 between 300 and 500, but common as far as 800 fathoms. It is known from 

 Arabia, South Africa, and the Crozet Islands to south-eastern Australia, the Gala- 



