A MONOGRAPH OF THE EXISTING CRINOIDS 53 



Diagnostic features. — A moderately slender species with 20 arms; the cirri, which 

 are arranged in 10 definite columns on a conical centrodorsal, are in general about one- 

 third the length of the arms; and the elements of the division series and first two bra- 

 chials have the median third smooth and the lateral thirds finely spinous or tubercular. 

 The arms are 100-130 mm. long, and the cirri, which are rather stout, are 35-47 mm. 

 long with 45-61 segments. 



Description. — The centrodorsal is conical, about 4 mm. broad at the base and 4 mm. 

 long. The cirrus sockets are arranged in 10 columns, 2 to each radial area, with 2 or 3 

 sockets to a column. The columns in each radial area are separated in the midradial 

 line by a broad bare more or less finely spinous area which is about equal in width to 

 a column of cirrus sockets. Outwardly the columns of cirrus sockets are in close 

 apposition with those of the adjacent radial areas. 



The cirri are XX, 45-54 (the longer 49-54), from 35 mm. to 42 mm. in length, and 

 stout. The first segment is short, and those following gradually increase in length to 

 the fourth, which is about twice as broad as long, and the fifth, which is about half 

 again as broad as long. The sixth is a transition segment, from half again to twice as 

 long as broad. The following segments gradually decrease in length, becoming about 

 as long as broad at about the eleventh and twice as broad as long after the fifteenth. 

 After the eighth or ninth the distal dorsal edge of the segments becomes slowly prom- 

 inent so that the segments after the fifteenth or sixteenth are provided with a high and 

 prominent dorsal spine as in the other species of the genus. 



The ends of the basal rays are visible as small but prominent tubercles in the angles 

 of the calyx. 



The radials are concealed by the centrodorsal, or just visible in the midradial line. 

 The IBri are more or less crescentic, convex proximally, about 4 times as broad as long, 

 with finely serrate edges and with the lateral two-thirds of the dorsal surface finely 

 spinous. The IBr 2 (axiUaries) are broadly pentagonal or rhombic, with blunted lateral 

 angles, twice as broad as long, with the edges finely serrate and the dorsolateral edge 

 bearing a few small spines. The IIBr series are 2. The division series and first brachials 

 are sharply flattened laterally. 



The 19 arms in the type specimen are 130 mm. long. The first brachials are 

 slightly wedge-shaped, about twice as broad as long exteriorly. The second brachials 

 are similar, but nearly twice as large. The first syzygial pan- (composed of brachials 

 3 +4) is oblong, half again as broad as long. The following 6 brachials are approximately 

 oblong, about two and one-half times as broad as long, then becoming very obliquely 

 wedge-shaped, half again as broad as long, toward the middle of the arm as long as 

 broad, distally less obliquely wedge-shaped, and terminally longer than broad. The 

 arms increase slightly in width to the twelfth or fourteenth brachials, then slowly taper 

 distally. The proximal third of the arm is very deep and strongly compressed laterally; 

 the outer two-thirds is rather sharply rounded dorsally. After the oblong proximal 

 brachials the distal ends of the brachials begin to project as a serrate overlap which 

 characteristically in the outer half of the arms becomes very pronounced and is 

 accompanied by a fine spinosity of the dorsal, but not lateral, surface. 



The pinnules are essentially as in C. aster. 



The color is bright yellow. 



