A MONOGRAPH OF THE EXISTING CRINOIDS 19 



Description. — The type series was composed of small individuals which were thus 

 described. The centrodorsal is long and columnar, with the tip conical. The cirrus 

 sockets are arranged in 10 columns of 2 each, the sockets of one column alternating with 

 those of the adjoining columns. 



The cirri are XX, 50-55, 25 mm. long. The segments in the basal half, except 

 for the proximal, are elongate, those in the distal half short with prominent dorsal 

 spines. 



The basals are just visible as small interradial tubercles. 



The radials are rather long. The IBri are about the size of the radials, and the 

 IBr 2 (axillaries) are widely pentagonal, broader than long; both have a high and sharp 

 median keel. The IIBr series are 2, like the IBr series and with a prominent keel. 



The 11-18 arms are 30 mm. long (only one-fifth longer than the cirri). The first 

 8 brachials are oblong, rather long, those following becoming wedge-shaped. All 

 the brachials are strongly carinate and laterally compressed. After the basal third 

 the arms become very narrow and the brachials begin to develop overlapping dorsal 

 spines. 



Pi is considerably the largest pinnule and is composed of 8-10 elongated segments. 

 The pinnules following decrease in length to P 6 or P 6 , then slowly increase in length 

 distally. 



The color in life is bright yellow. 



In fully grown individuals the arms are 19-20 (usually 20), about 80 mm. long; 

 the cirri are composed of about 70 segments and are 45-50 mm. long. 



Notes. — In a specimen from Mortensen's station 7, according to Gislen, the cen- 

 trodorsal is a high cone 2.8 mm. broad at the base and 2.6 mm. high. The bare dorsal 

 pole is 2.4 mm. in diameter and is covered with pits and tubercles. There are 5 strong 

 interradial ridges. The cirrus sockets are arranged in 10 columns of 2 or 3 each. There 

 is a tubercle on each side of the nerve lumen. 



The cirri are XXIII, 57-78, 25-45 mm. long. The sixth-seventeenth cirrus 

 segments are slightly longer than broad. Dorsal spines are developed from the fifteenth 



onward. 



The radials are visible in the interradial angles of the calyx. The IBr, are five 

 times as broad as long with an abrupt high bidentate crest in the median line. The 

 IBr 2 (axillaries) are twice as broad as long with a median sharp and simple crest in the 

 proximal three-fourths, and a synarthrial backward projection. The IIBr series are 

 2 with a carination similar to that of the IBr series but lower and not serrate. 



The 20 arms are all broken. The carination continues to the ends of the arms. 

 Overlapping dorsal spines are developed from the fifth brachial onward. 



The distal intersyzygial interval is 5-7 muscular articulations. 



P, is 11 mm. long with 19-20 segments. P 2 is 8 mm. long with 13 segments. P» 

 is 7.5 mm. long with 12 segments. P< is 4.5 mm. long with 8 segments. P 5 is 3.7 mm. 

 long with 7 segments. The distal pinnules are 7 mm. long with 16 segments. 



The diskis7.5 mm. in diameter with sparse calcareous granules along the ambulacral 

 furrows. The anal cone is 2 mm. high and bears granules. 



The color in alcohol is brown, the ossicles somewhat brighter. 



Another specimen from Mortensen's station 7 has the cirri XIX, 59-77, 26-38 

 mm. long. The 20 arms are 65 mm. long. P, is 6.2 mm. long with 11 segments. 



