A MONOGRAPH OF THE EXISTING CRINOIDS 473 



recognizing the genus).— GislSn, Zool. Bidrag Uppsala, vol. 9, 1924, p. 150 (compared with 

 Solanocrinus costatus); Kungl. Fysiogr. Sallsk. Handl., new ser., vol. 45, No. 11, 1934, p. 47. 



Diagnosis. — A genus of Mariametridae in which P 2 is the longest pinnule, usually 

 much longer than P 3 , and tapers gradually to a slender and delicate tip; the division 

 series are usually in very close lateral contact with more or less broadly and sharply 

 flattened sides, more rarely just in contact with the sides slightly or not at all flattened ; 

 the cirri are rather short, with not more than 30 segments, of which the outer are 

 carinate, rarely more or less spinous, dorsally; and the dorsal surface of the division 

 series is smooth, without ornamentation. 



Geographical range. — From Hongkong and the Philippines to the Caroline, 

 Marshall, and Hawaiian Islands, Fiji, the Tonga Islands, New Caledonia, the Solomon 

 Islands, northern Australia south to Cape Hillsborough, Queensland, and the Abrolhos 

 Islands and possibly Perth, Western Australia, and westward to the eastern coast of 

 Africa from the Red Sea south to Dar-es-Salaam, Tanganyika Territory. 



Bathymetrical range. — From the shoreline down to 51 (?54) meters. The species 

 are essentially littoral reef-inhabiting forms. 



Remarks. — The genus Lamprometra as considered herein includes two species, 

 one, L. klunzingeri, characterized by slender proximal pinnules of which the basal 

 segments are either not at all or only very slightly carinate, occurring from the Red 

 Sea to Muscat and southward possibly to Dar-es-Salaam, and the other, L. palmata, 

 with one or more of the proximal pinnules either enlarged or strongly carinate, occur- 

 ring from Baluchistan eastward to northern Australia, Polynesia, the Philippines, 

 and Hongkong. 



It is quite possible that L. klunzingeri is simply the western form of L. palmata, 

 although on the basis of the material examined it appears to be quite distinct, the 

 entire or almost complete absence of carination on the basal segments of the proximal 

 pinnules being diagnostic. 



Generally speaking, among the Mariametrida in forms in which the lower pinnules 

 are carinate the carination disappears if the lower pinnules are enlarged, so that strong 

 carination or enlargement of the lower pinnules are alternative conditions. This is 

 well seen in the genus Himerometra in which H. persica and H. bartschi have slender 

 and strongly carinate proximal pinnules, and the other species very stout proximal 

 pinnules, which are not carinate basally. 



It seems reasonable, therefore, to consider L. klunzingeri, with noncarinate 

 slender proximal pinnules, as distinct from L. palmata, of which one form {palmata) 

 has P 2 much enlarged and the other (gyges) has P 2 slender and strongly carinate 

 basally. 



Lamprometra palmata is always easily distinguished from all other comatulids, 

 but at the same time it is the most variable species known, and scarcely any two indi- 

 viduals are quite alike. The cirri are usually carinate dorsally on the distal segments, 

 but these may be rounded dorsally, or they may bear more or less conspicuous spines. 

 The earlier segments may be broader than long, like the distal, or as long as, or even 

 longer than, broad, and markedly longer than the distal segments. The postradial 

 series may be in close lateral apposition and broadly and sharply flattened laterally, 

 or quite separated without any trace of lateral flattening, or in any intermediate con- 

 dition. P 2 is always the longest or the stoutest pinnule, but it varies from very stout 



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