A MONOGRAPH OF THE EXISTING CRINOIDS 201 



KEY TO THE GENERA OF THE FAMILY CHARITOMETRIDAE 



a 1 . Genital pinnules tapering evenly from the usually more or less broadened earlier segments to a 

 delicate tip, the portion beyond the gonads being much longer than the gonads themselves. 

 &i. Outer portion of the arms strongly compressed laterally, the dorsal surface rising evenly into a 

 more or less sharp keel in the middorsal line, the keels on each brachial forming a high over- 

 lapping spine or tubercle; ossicles of the division series and first two brachials with the central 

 portion elevated, V-shaped in cross section; centrodorsal more or less columnar, the cirrus 

 sockets in 5 or 10 columns; 10 arms 75-211 mm. long (southern Philippines to Timor; 520-1,334 



meters ) Chondrometra (p. 201) 



&». Outer portion oVthe arms rounded dorsally, with or without a fine median abruptly raised line, 

 c'. Oral pinnules little or not at all longer than the middle and distal pinnules. 



d' Ossicles of the division series rising to a prominent narrow, high, smooth, and pointed 

 synarthrial tubercle the profile of which forms an acute angle; IIBr series 2; opposing 

 spine often or usually forked (Philippine Islands southward to the Kei Islands and the 



Sahul Bank; 104-704 meters) Monachometra (p. 208) 



cP Synarthrial tubercles, if present, low and broadly rounded, the profile a broadly rounded 

 obtuse angle; IIBr series 4(3 + 4), occasionally 2; opposing spine never forked (western 

 Indian Ocean from Sokotra south to East London, South Africa, and eastward to Timor, 

 the Sahul Bank, the Kermadec Islands, Fiji, and the Hawaiian Islands, and northward 



to southern Japan; 55-2,194 meters) Glyptometra (p. 227) 



c* Oral pinnules markedly longer than the very short middle and distal pinnules (from the 

 Yucatan Bank, the Florida Keys, northern Cuba, and the southern Bahamas eastward 



and southward to Barbados and Grenada; also St. Helena; 139-707 meters). 



Crinometra (p. 279) 



a' Genital pinnules with from two to four segments much broadened, the broadening ending abruptly 

 and being succeeded by a slender distal portion shorter than the much swollen and prominent 

 ovoid gonads; size medium or small, the arms not over 110 mm. and usually less than 100 mm. 



6' CenTrfdorsal sharply conical, higher than broad at the base, with the cirrus sockets in 5 columns 

 single or partially double, one in the middle of each radial area, the columns being separated 

 by broad interradial spaces; 14-20 arms 60 mm. long, the IIBR series 2; opposing spine forked 

 (southwestern Japan to the Bonin Islands; 165-210 meters).. ....Chlorometra (p. 221) 



6> Centrodorsal hemispherical or discoidal, much broader at the base than high, with the cirrus 



sockets in irregular marginal rows, not segregated into distinct columns; 10 arms 



c> Division series and arm bases compressed, their profile making a small angle with the dorso- 



ventral axis; at least 15 cirrus segments; larger, the arms 90-110 mm. long 



d' Ossicles of the division series and lower brachials in close lateral contact, without modified 



lateral borders, and broadly and sharply flattened against their neighbors (kermadec 



Islands to Fiji; 1,152 meters) Charito metra (p. 347) 



d> Ossicles of the division series and lower brachials relatively narrow and well separated from 

 their neighbors, the gap between them more or less completely bridged by a thin flange- 

 like production of the dorsolateral margin of the ossicles which persists as far as the 

 fourth or fifth brachials (Celebes to Mindanao; southwestern Japan; 660-1,327 meters,!. 



Poecilometra (p. 354) 



<* Divis'ion's'eVies'and arm bases more orTess "recumbent, their profile making a large angle with 

 the dorsoventral axis; not more than 15 cirrus segments; smaller, the arms not over 75 

 mm., and rarelv over 45 mm., long (Timor and the Kei Islands northward to southwestern 



Japan; 180-1,165 [71,264] meters) Strotometra (p. 36U 



Genus CHONDROMETRA A. H. Clark 

 Antedon (part) P. H. Carpenter, Challenger Reports, Zoology, vol. 26, pt. 60, 1888, p. 128, and 



following authors. 1M , ,„, 



Charitometra (part) A. H. Clark, Smithsonian Misc. Coll., vol. 50, pt. 3, 1907, p. 361. 



