292 BULLETIN 82, UNITED STATES NATIONAL MUSEUM 



are either 4(3+4) or 4(1+2, 3+4). The full complement of IIIBr series is never 

 present. The division scries and lower brachials are slightly convex dorsally and are 

 laterally in close apposition and sharply flattened. The elements of the IBr series are 

 thickly and evenly covered with prominent tubercles resembling those on the dorsal 

 pole of the centrodorsal. These sometimes arrange themselves in a linear series in tho 

 median line, or there may be a more or less distinct median keel which, however, is 

 never well marked. This evenly tubercular ornamentation may encroach somewhat 

 upon the lower elements of the IIBr series, and always extends for a considerable dis- 

 tance up into the interradial angles and also between the IIBr series, narrowing to 

 a point distally. The elements of the IIBr and IIIBr series and the lower brachials 

 have more or less — usually strongly — crenulate or tubercular edges, and their dorsal 

 surface usually bears a few small scattered tubercles. Along the median line they bear 

 large and prominent dorsoventrally elongate, narrow, dorsally rounded tubercles which 

 form a conspicuous narrow carination. 



The lower brachials have very strongly dentate or tubercular distal ends in the 

 center of which is a single large tubercle. These brachial tubercles form a median line 

 of tubercles along the arm that continues the carination of the division series out 

 along the arms, where it gradually dies away and disappears at about the end of the 

 proximal fourth. The prominent eversion of the distal edges of the brachials becomes 

 distally less strongly dentate, at the same time becoming less and less erect, until at 

 about the twentieth brachial it becomes merely a moderately marked finely spinous 

 overlap and so continues to the end of the arms. The brachials as far as about the 

 twentieth are sharply flattened laterally. 



P D is 13 mm. long, evenly tapering and becoming slender distally, with 30 segments 

 which at first are about three times as broad as long, becoming about as long as broad 

 distally; the first four or five segments are slightly carinate. Pi is 14 nun. long, slightly 

 more slender basally than P D , with slightly longer segments which become about one- 

 third again as long as broad distally; the lower segments are not carinate. P 2 is 13 mm. 

 long. P a is 12 mm. long. P 4 is 11 mm. long, becoming progressively more expanded 

 basally but tapering evenly and very slender in the distal half. The pinnules following 

 still further decrease in length and increase in basal stoutness, P 7 being 8 mm. long with 

 15 segments of which tho third, fourth, and fifth are expanded, the fourth most so, 

 and the remainder are slender. For some time the pinnules are similar to P 7 , after 

 which they gradually lose the basal expansion and increase in length to 10 nun. 



In alcohol the color is dull yellowish or light yellowish brown, the calyx and arm 

 bases to tho third brachial often dark yellowish brown. 



Notes. — A much more detailed description of this form is based upon one specimen 

 from St. Vincent without further data, one from Blake station 34, one from Blake 

 station 158, and four specimens and fragments of a fifth from Blake station 157, under 

 tho name of Antedon brevipinna var. decora. The specimen from St. Vincent had an 

 arm length of about 85 mm.; that from Blake station 34 an arm length of about 75 mm.; 

 that from Blake station 158 an estimated arm length of 90 mm.; and the four from 

 Blake station 157 had arms 65, 75, 80, and 85 mm. long. 



The centrodorsal is very flat. The bare dorsal pole is fiat, sharply delimited, 

 bearing fine protuberances — small spines, tubercles, or teeth, in part isolated though as a 

 rule united into sinuous bands — which are closely set and dark colored. Spiny and 



