488 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 39, 



than in the habitat of his specimen, which I suspect was a commercial 

 specimen obtained through Mr. Alan Owston from Japanese fisher- 

 men living at Sagami Bay. 



In the sample examined by him Doctor Palmer found the propor- 

 tions of CaO and MgO to be as follows : 



CaO = 49.95% (equivalent to CaCOg 89.19%); 

 MgO = 4.89% (equivalent to MgCOg 10.29%,)- 

 He notes, further, that "this specimen is white and quite free from 

 extraneous material." 



HELIOMETRA GLACIALIS var. MAXIMA. 



Antedon escJirichtii var. viaxima A. H. Clark, Proc. U. S. Nat. Mus., vol. 33, 

 1907, p. 75. 



Locality.— Albatross station 4986; lat. 43° 01' 40" N.; long. 140° 

 22' 40" E. (Benkei Mizaki light bearing N. 35° E., 15 miles distant), 

 in Iwanai Bay, northeastern part of the Sea of Japan; depth, 172 

 fathoms; bottom temperature, 33.9° F.; surface temperature, 69° F.; 

 surface density, 1.02405. 



In this specimen Doctor Palmer found : 

 CaO = 40.03%o (equivalent to CaCOg 71.48%); 

 MgO = 2.68% (equivalent to MgCOg 5.61%) : 

 and he adds that "this specimen contains much foreign material, 

 chiefly organic; on the basis of purity as found in the other speci- 

 men, the content of magnesium carbonate (MgCOg) in this specimen 

 may be accepted as 7 per cent." 



This species is the largest crinoid known, measuring about three feet 

 across its extended arms. It might be supposed that the comparative 

 openness of its skeleton was due to this very large size as a result of 

 the deposition of inorganic matter not keeping pace with the rapid 

 increase in bodily size. It is noticeable, however, that the crinoids of 

 the deep seas and from the colder regions have more delicate and 

 more open skeletons 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 depo- 

 sition of inorganic matter more difficult; but from 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 con- 

 tinued in those of the polar regions points to the conclusion that the 

 chief factor involved is temperature rather than pressure. 



