PART 5 A MONOGRAPH OF THE EXISTING CRINOIDS 525 



Siboga station 45; Flores Sea, north of Sumbava (lat. 724' S., long. 118 15'12" 

 E.); 794 meters; fane gray mud with some radiolarians; April 6, 1899 [A. H. Clark, 

 1912, 1918] (2, Amsterdam M.). 



Albatross station 5284; Balayan Bay, between southern Luzon and Mindoro; 

 Malavatuan Island (S.) bearing N. 46 W., 14.25 miles distant (.lat. 1342'05" N., 

 12030'45" E.); 771 meters; temperature 5.72 C.; gray mud and globigerinae ; July 20, 

 1908 [A. H. Clark, 1911] (2, U.S.N.M., 27508, 36276). 



Dr. Sixten Bock's Expedition to Japan station 6; Kagoshima and Okinoshima, Kiu 

 Shin; 110 or 201-402 meters; May 13-14, or 18, 1914 [Gisten, 1922]. 



Dr. Th. Mortensen, May 13, 1914; station 6, 16 miles W. to S. from Bonomisaki, 

 Kiu-Shiu, Japan; 366 meters [Gislen, 1927] (3, C.M.). 



Dr. Th. Mortensen, June 10, 1914; station 18, off Misaki, Japan; 457 meters 

 [Gislen, 1927] (l, C.M.). 



Afabahiss station 109; Zanzibar area (lat. 510'36" S., long. 3933'48" E.); 640 

 meters; temperature at 627 meters, 8.86 C., salinity 34.84% ; bottom light gray mud 

 [A. H. Clark, 1937] (1, B.M.). 



Geographical range. From off Zanzibar to southwestern India, New Guinea, the 

 Philippines and southwestern Japan. 



Bathymetrical range. From 366 (?201) to 924 meters; the average of 16 records 

 is 595 meters. 



Thermal range. From 5.72 C. to 13.3 C.; the average of 5 records is 9.02 C. 



Salinity range. The single record is 34.84 parts per thousand. 



Remarks. With Ps. mira, described in 1909, 1 have united as synonyms Ps. parva, 

 described in 1911, Ps. major and Ps. inusitata described in 1912, and Ps. wireni de- 

 scribed by Dr. Torsten Gislen in 1922. 



The types of Psathyrometra mira, Ps. major, and Ps. parva are all quite alike except 

 for a difference in size and in the details of the arrangement of the cirrus sockets on the 

 centrodorsal. In Ps. major the median column of cirrus sockets in each radial area con- 

 sists of 2, or of 2 and a more or less developed third, sockets. In Ps. mira there is only a 

 single median socket, and in Ps. parva there are only the 2 lateral columns. But in a 

 specimen from Investigator station 116 there are only the 2 lateral columns in 2 radial 

 areas while there is a single median socket in each of the other 3, disposing of the sup- 

 posed difference between Ps. parva and Ps. mira; and Ps. mira intergrades with Ps. 

 major in the same way. 



The specimens which have been referred to Ps. inusitata are all small; but the 

 centrodorsal is sharply conical as in the others. About the dorsal pole there are a 

 number of obsolete cirrus sockets which appear to be arranged in alternate rows without 

 any trace of a segregation into radial areas, as in the species of Bathymetrinae. But 

 on the rest of the centrodorsal the cirrus sockets are assuming a columnar arrange- 

 ment which is obviously the same as that characteristic of Ps. mira. The IBr series 

 and lower brachials resemble those of some of the Bathymetrinae more than they do 

 those of Ps. mira. But this form is common to most young comatulids and can. I 

 think, be safely regarded as a condition correlated with' the condition of the centro- 

 dorsal. 



The pinnules of Ps. inusitata resemble those of Ps. mira, which are of a quite 

 unusual kind, and this correspondence in the pinnulation seems to me more than to 

 outweigh the differences in the basal arm structure. 



