A MONOGRAPH OF THE EXISTING CRINOIDS 429 



iu their basal portion, witli the fii-st seven or eight brachials sharply flattened laterally, 

 very gradually becoming narrower and distally strongly carinate. At about the 

 twelfth or fifteenth brachial a broadly rounded median keel begins to be indicated; 

 this gradually narrows distally and on the twentieth to the twenty-fifth brachial the 

 median portion of the distal edge begins to be slightly prominent. These features 

 increase slowly in extent, the median keel at the same time narrowing, so that the 

 brachials in the outer half of the arms are bluntly carinate with the median portion 

 of the distal edge produced, and in the terminal portion sharply carinate with promi- 

 nent overlapping spmes. 



Pi is 8 mm. long, strongly prismatic, slightly less stout than the succeeding pin- 

 nules, with 16 segments of which the first is short, the second and third are about as 

 long as broad, and the remainder are very slightly longer than broad, becoming about 

 one-third again as long as broad distally. Pj is 12.5 mm. long with 19 segments of 

 which the first is twice as broad as long, the second is about as long as broad, and the 

 remainder are very slightly longer than broad. The more distal segments exhibit a 

 tendency toward a slight production of their distal edges at the prismatic angles. 

 The terminal 3 or 4 segments taper rather more rapidly than usual. P3 is 14 mm. long 

 with 17 segments of which the first is twice as broad as long, the second is about as long 

 as broad, and those following very gradually become longer than broad and twice as 

 long as broad in the terminal portion. The last six segments taper rather rapidly, 

 and the last two are minute. From the fourth segment onward small spines are 

 developed on the distal border of the segments and on the distal keel of the pinnule, 

 and on the last 4 segments there is in addition a somewhat longer spine developed on 

 the corresponding interior angles. P4 is 15 mm. long with 16 segments, all but the 

 basal of which are proportionately longer than those of P3, the distal with long spines 

 on their prismatic angles, P5 is similar, slightly longer. Pj is similar, 17 mm. long. 

 Pio is 19 mm. long with 20 segments which become elongate distally and bear long 

 spines at the prismatic angles. In the terminal portion of the arms the pinnules 

 slowly decrease in length. The abrupt distal taper gives the pinnules the appearance 

 of having been broken off and subsequently repaired. 



Description of a specimen from Investigator station 387. — The centrodorsal is 

 thick discoidal, about twice as broad at the base as high; the dorsal pole bears 5 

 irregular interradial tubercles. The cirrus sockets are arranged in 10 columns, 2 or 

 3 to a column. These columns are equidistant from each other and, though entirely 

 free, are only very slightly separated. 



The cirri are XXV, 72-88, from 46 mm. to 54 mm. in length. The first segment 

 is short and those following gradually increase in length becoming about as long as 

 broad on the ninth or tenth, about one-third again as long as broad on the fourteenth, 

 and after the twenty-second or twenty-third gradually decreasing in length so that 

 those in the distal fourth of the cirri are about three times as broad as long. From 

 the fifth or sixth to about the twenty-third the segments bear very prominent, though 

 not very long, overlapping ventral spines which are rather strongly curved on their 

 ventral profile so that at the tip they are almost parallel with the longitudinal axis 

 of the" cirri. The short distal segments bear broad dorsal spines. 



The ends of the basal rays are visible as very small triangular areas in the inter- 

 radial angles of the calyx. 



