A MONOGRAPH OF THE EXISTING CRINOIDS 229 



all the cirrus segments are much broader than long to species in which all but two or 

 three of the basal segments are much longer than broad. In both groups the number 

 of arms in the included species runs from 10 to 32 or 33, and in both groups the division 

 series and arm bases may be plain or may have a more or less developed usually rugose 

 ornamentation. In both groups the subdivisions are based upon the relative length of 

 the proximal and distal cirrus segments and the ornamentation. In the group with 

 slender and long-segmented cirri the arrangement of the cirrus sockets on the centro- 

 dorsal, whether in 10 or 15 columns, seems to be significant when fully matured indi- 

 viduals are compared, though species normally with 15 columns of cirrus sockets when 

 adult may have only 10 when young. 



History. The species of this genus known to Carpenter were assigned by him to 

 Antedon. All of them were transferred to Charitometra when I established that genus 

 in 1907. In 1909 I transferred some of the species of Charitometra to the new genera 

 Glyptometra and Pachylometra, and in 1916 I established the genera Crossometra and 

 Perissometra for species previously included in Pachylometra, and Calyptometra for one 

 of the species included in Glyptometra. 



KEY TO THE SPECIES IN THE GENUS GLYPTOMETRA 



a 1 . Cirri stout, the longest segments at most only slightly longer than broad. 



b 1 . All the cirrus segments much broader than long, the longest from half again to twice as broad 

 as long; ossicles of the IBr series and first four brachials with the dorsal surface raised into a 

 broad blunt median tubercle, highest and most conspicuous on the division series; brachials 

 in the proximal fourth or third of the arm with indications of a broad low median tubercle; 

 10 arms 165 mm. long; cirri with 17-20 segments, 20-25 mm. long (Timor to northern Celebes; 



457-520 meters) timorensis (p. 230) 



b 2 . Longest cirrus segments about as long as broad or slightly longer than broad. 



c 1 . Lower brachials with the distal ends thickened or everted, standing up more or less prom- 

 inently above the general surface of the ossicles; 10-20 arms 100-180 mm. long; IIBr series 

 usually 4 (3 + 4) (Celebes to the Kei Islands and Timor and west to the Nicobar Islands; 



245-1,023 meters) crassa (p. 237) 



c 2 . Lower brachials smooth, without projecting distal ends. 



d 1 . Cirri of uniform width throughout, all the segments subequal, about as long as broad; 

 11-20 arms 100-145 mm. long (Philippines to Fiji and the Kermadec Islands; 1,152 



meters) inaequalis (p. 343) 



d 1 . Cirri broader distally than proximally, the longest segments about as long as broad, the 

 distal becoming slightly broader than long; 33 arms 130 mm. long (southern Japan; 366 



meters) sep ten trionalis (p. 246) 



a 2 . Cirri more slender, the longest segments, and often all the segments, markedly longer than broad. 

 6 1 . Ossicles of the division series and all, or nearly all, the brachials with a low, narrow, sharp 

 median keel of uniform height; ossicles of the division series and earlier brachials with abruptly 

 everted borders and more or less numerous small beady tubercles or capitate spines scattered 

 over the dorsal surface; 10-18 (usually 10-12) arms 100-140 mm. long; IIBr series, when 

 present, 4(3 + 4) or 2 (northern Philippines to the Kei Islands; 245-929 meters). 



tuberoaa (p. 232) 

 V. No narrow median raised line on the ossicles of the division series and arms, which are without 



small beady or capitate tubercles. 



c 1 . Cirrus sockets arranged in 10 columns on the centrodorsal. 

 d 1 . Cirri stouter, the distal segments not longer than broad. 



e l . Distal cirrus segments broader than long; 14-33 arms 100-205 mm. long (northern 

 Mindanao to the Kei Islands; 252-773 meters) distincta (p. 249) 



