210 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



The 20 arms are about 175 mm. long and are composed of about 160 brachials, of 

 which the fourth and following are short and nearly oblong, their surface rising con- 

 siderably from the proximal to the distal ends, which stand up rather prominently. 

 Beyond the fifteenth the brachials are more triangular, with a median ridge, and overlap 

 slightly. 



Syzygies occur between brachials 3+4, again from between brachials 19 + 20 to 

 between brachials 21+22, and distally at intervals of from 5 to 9, usually 7 or 8, oblique 

 muscular articulations. 



Pi is about 8 mm. long and consists of about 25 short segments the lowest of which 

 are broad and rather sharply flattened. P 2 is a trifle longer and stouter with a smaller 

 number of larger segments. In the next following pinnules the segments gradually 

 increase in size and become more carinate, the third-fifth being the broadest; but they 

 do not become longer than broad until some way out on the arm. The genital pinnules 

 have a covering of small plates with the sacculi scattered upon them, and the ambulacra 

 of the later pinnules have well differentiated side plates with intervening sacculi. 



The disk is 10 mm. in diameter and is thickly plated, as are the arms, both along 

 the ambulacra and in the intermuscular spaces. 



The color in alcohol is whitish brown, the disk darker. 



Notes. — Professor Gislen noted that the Challenger specimens in the British Museum 

 represent two widely different forms. 



In the first form the centrodorsal is discoidal; the cirri are stout and are arranged 

 in 12 columns, and have a dorsal spine and keel and a simple opposing spine. Ho 

 remarked that one specimen with only 10 arms is, as is often the case, the larger one. 

 This form, he said, should be referred to Mormchometra. 



In the second form the centrodorsal is sharply conical; the cirrus sockets are 

 striated as in some fossil comatulids. The cirri are in 10 columns without dorsal 

 spines and with a double opposing spine. The brachials are collar shaped. He said 

 that the arms are very similar to those of Diodontometra, but the arrangement of the 

 cirri is different. He noted that this seems to be the type described and figured by 

 Carpenter. 



Of the three specimens from Albatross station 5356 one has 14 arms about 170 

 mm. long and the cirri XXII, 19-22, about 30 mm. long, with a single large and promi- 

 nent opposing spine; another has 16 arms about 170 mm. long and the cirri XX, 18-20, 

 30-33 mm. long with the opposing spine large and prominent and usually forked at 

 the tip; and the third has 20 arms and the cirri XXV, 17-22, 30-37 mm. long with 

 the opposing spine single. 



One of the two specimens from the Danish Expedition to the Kei Islands station 

 3 has 20 arms 115 mm. long, with ten IIBr 2 series; the longest cirri are 32 mm. long 

 with 19-20 segments. The other specimen from station 3 has 20 arms 160 mm. long. 



The three specimens from the Danish Expedition to the Kei Islands station 3 

 may be described as follows. 



The centrodorsal is stout, conical, not so high as broad at the base, with the 

 cirrus sockets arranged in 10 crowded columns of 2 or 3 each. 



The cirri are XXV, 18-20, long and stout, 35 mm. long. The first segment is 

 very short, the third is half again as broad as long, the fourth-sixth or -seventh are 

 half again as long as broad, and those following are slightly shorter, but the last two 



