A MONOGRAPH OF THE EXISTING CRINOIDS 379 



Actinometra echinoptera var. valida-meridionalis HABTLAUB, Mem. Mus. Comp. Zofil., vol. 27, 



No. 4, 1912, p. 417 (Blake station 272). 

 Actinometra echinoptera var. rubiginosa (part) HARTLAUB, Mem. Mus. Comp. Zofil., vol. 27, No. 4, 



1912, p. 436; pi. 17, fig. 13 (Blake station 157). 

 Actinometra echinoptera var. pulchella (part) HARTLAUB, Mem. Mus. Comp. Zo61., vol. 27, No. 4, 



1912, p. 442 (last record on page; 23 32' N., 88 05' W.). 

 Comactinia (Actinometra) meridionalis GOLDRING, Review of the Criiioidea Flexibilia, 1921, p. 3. 



Diagnostic features. The cirri, which are relatively short, rather stout, strongly 

 curved, and composed of 8-12 segments, of which the distal, which are shorter than 

 the proximal, are somewhat longer than broad, or at least no broader than long, and 

 are entirely without dorsal spines or other processes and only slightly compressed 

 laterally, distinguish this species at once from all the other Atlantic species of Comas- 

 teridae. The mouth is marginal and the anal cone usually occupies the center of the 

 disk. The arms in adults vary from 40 to 150 mm. in length. They may be short 

 and robust, exceedingly slender and elongated, or very robust proximally, increasing 

 in width from the first to about the fourteenth brachial and thence gradually tapering 

 and becoming greatly attenuated distally. In large and well-developed individuals 

 the exceedingly strong dorsal processes on the segments of the lower and middle pin- 

 nules are very characteristic, making detached arms very easy to determine. 



As a general rule the size increases proportionately with the depth, the smallest 

 examples being those taken along the shores and the largest those from about 200 

 meters or over. 



A specimen from Charleston has the arms about 45 mm. long and the cirri XXVI, 

 12, about 10 mm. long, arranged in one and a partial second row on a discoidal centro- 

 dorsal, of which the bare dorsal pole is 3 mm. in diameter. 



In some others from off Habana in deep water the arms are 150 mm. long, stout 

 basally but becoming very slender distally, instead of being robust throughout as in 

 that from Charleston, and the cirri are XV-XX, 8-12, from 10 to 12 mm. long, the 

 discoidal centrodorsal having a dorsal pole 4 mm. in diameter. 



Description. The centrodorsal is large, discoidal, with the bare polar area large, 

 4 or 5 mm. in diameter, flat or with a broad shallow central pit. 



The cirri are XV-XX, 9-12 (usually 11), short and rather stout, from 10 to 12 

 mm. in length. The first segment is short, the second is usually about as long as 

 broad, and the third and fourth are from half again to twice as long as broad. The 

 following segments decrease gradually in length, the seventh and following being about 

 as long as broad, or very slightly longer than broad. The antepenultimate segment is 

 slightly longer, and the penultimate slightly shorter, than the segment preceding the 

 former. The third and fourth segments are slightly constricted centrally. The 

 cirri are smooth dorsally, the segments being without dorsal processes or overlapping 

 ends. The opposing spine is small, erect, median in position. The terminal claw is 

 about as long as the antepenultimate segment (considerably longer than the penulti- 

 mate), and is stout and strongly curved basally, but becoming slender and nearly 

 straight distally. The cirri are slightly compressed in the distal half. 



The ends of the basal rays are visible in the interradial angles of the calyx, 

 though they are not prominent. 



