MONOGRAPH OF THE EXISTING CRINOIDS. 297 



than those from comparatively shallow water in the tropics, and it therefore seems 

 most probable that cold has the effect of retarding the deposition of inorganic 

 matter by the animals to a far greater degree than it retards the general body 

 development. Probably in the deep-water forms the enormous pressure under 

 which the animals live also tends in various ways to make the deposition of 

 inorganic matter more difficult; but the fact that among the crinoids the skeletal 

 conditions found in the inhabitants of the deep sea are to almost or quite the same 

 degree repeated or continued in those of the polar regions points to the conclusion 

 that the chief factor involved is temperature rather than pressure." 



The great discrepancy in the proportion of magnesium in the skeletons of these 

 two crinoids, one from relatively warm and one from very cold water, aroused 

 Professor Clarke's interest, and he suggested the advisability of more extended in- 

 vestigations. I sent him the following material: 



Capillaster multiradiata. Philippine Islands, 1.3 miles from Jolo Light, Jol6 

 (lat. 6 04' 25" N., long. 120 58' 30" E.) ; depth, 36 meters; no temperature 

 record (Albatross Station 5137). 



Zygometra microdiscus. Aru Islands, anchorage off Pulu Jedan (Pearl 

 Banks) ; depth, 13 meters; no temperature record (Kiboga Station 273). 



Catoptometra opkiura. Philippine Islands, North Balabac Strait, 15.5 miles 

 from Balabac Light (lat. 8 06' 40"' N., long. 117 18' 45" E.) ; depth, 104 meters; 

 no temperature record (Albatross Station 5036). 



Heterometra quinduplicava. Philippine Islands, 3.3 miles from Tinakta 

 Island, Tawi Tawi group, Sulu (Jolo) Archipelago (lat. 5 12' 30" N., long. 119 

 55' 50" E.) ; depth, 32 meters; no temperature record (Albatross Station 5157). 



Tropiometra picta. Rio de Janeiro, Brazil. 



Ptilometra mulleri. Sydney, New South Wales. 



Parametra granulata. Philippine Islands, between Negros and Siquijor, 11.8 

 miles from Apo Island (lat. 9 15' 45" N., long. 123 22' 00" E.) ; depth, 502 

 meters; temperature, 11.95C. (Albatross Station 5536). 



Perissometra patula. Philippine Islands, North Balabac Strait, 15.5 miles 

 from Balabac Light (lat. 8 06' 40" N., long. 117 18' 45" E.) ; depth, 104 meters; 

 no temperature record (Albatross Station 5036). 



Chondrometra rugosa. Lesser Sunda Islands, near Rotti (lat. 10 39' S., 

 long. 123 40' E.) ; depth, 520 meters; no temperature record (Siboga Station 297). 



Crinometra concinna. Northern coast of Cuba (lat. 23 10' 35" N., long. 82 

 20' 24" W.) ; depth, 59 meters; temperature, 26.17 C. (Albatross Station 2324). 



Promachocrinus kerguelensis. Shores of the Antarctic Continent, in the 

 vicinity of Gaussberg (approximately lat. 67 S., long. 90 E.) ; depth, 350-400 

 meters; temperature, 1.85 C.; salinity, 3.3 percent (Gauss). 



Florometra asperrima. Coast of Washington (lat. 47 29' 30" N., long. 125 

 43' 00" W.) ; depth, 1,145 meters; temperature, 3.28 C. (Albatross Station 3070). 



Anthometra adriani. Shores of the Antarctic Continent, in the vicinity of 

 Gaussberg (approximately lat. 67 S., long. 90 E.) ; depth, 350-400 meters; tem- 

 perature, 1.85 C.; salinity, 3.3 per cent (Gauss). 



