A MONOGRAPH OF THE EXISTING CRINOIDS 247 



(usually 15-20) arms, which are 60-145 mm. long, are composed of very short 

 brachials. 



Description. — The centrodorsal is discoidal, moderately thick, with the bare 

 dorsal pole flat, 4 mm. in diameter. The cirrus sockets are arranged in one and a 

 partial second irregular and closely crowded marginal rows. 



The cirri are XXI, 32-36, 30 mm. long, moderately slender. The first segment 

 is very short, and those following gradually increase in length to from the eighth to 

 the thirteenth, which, with those following, is about as long as broad. The cirri 

 decrease almost imperceptibly in width from the base outward and more rapidly on 

 the last six or eight segments. On the terminal four to six segments the dorsal 

 surface is slightly swollen so that the dorsal profile is slightly convex, the highest 

 point in the convexity of the antepenultimate segment being beyond the middle. 

 The middorsal line of the last five segments is more or less sharoly carinate. The 

 opposing spine is small, terminal, with the dorsal profile usually rising in a straight 

 line from the proximal end of the segment; but occasionally the apex is slightly 

 produced. 



The radials are concealed by the centrodorsal except for their distal angles, which 

 are visible interradially as low triangles with the produced apices reaching about 

 halfway to the midradial line. The IBr, are very short, six to eight times as broad 

 as long, slightly incised in the midradial portion of the distal edge. The IBr 2 (axil- 

 laries) are short, two to three times as broad as long, triangular with the lateral 

 angles truncated, forming sides that are slightly shorter than the lateral borders 

 of the IBr,. The distal borders are nearly straight and the distal angle is somewhat 

 greater than a right angle. The lateral borders of the elements of the division series 

 are slightly produced and are in lateral contact. There are present eight IIBr 4 (3+4) 

 series and eight IIIBr 2 series. 



The 26 arms are 145 mm. long. The brachials beyond the proximal fourth of 

 the arm are exceedingly short, four or five times as broad as long, and practically 

 oblong. 



P, is about 12 mm. long, with 25 segments. It tapers from the third to the tenth 

 or eleventh segment and is very slender and delicate from that point onward. The 

 basal segments are broader than long, the eighth segment is about as long as broad, 

 and the outer are about half again as long as broad. The second-seventh segments 

 have a prominent, though narrow, carinate process the crest of which is straight and 

 parallel with the axis of the segment. This is highest on the fourth segment and 

 slowly decreases in height distally. The outer surface of the earlier segments is 

 swollen, this swelling gradually narrowing and in the outer half of the pinnule becoming 

 a sharp gablelike ridge. 



On arms arising from a IIIBr series P, is 15 mm. long, with 33 segments, and 

 tapers much more gradually, thus more nearly resembling P 2 . P 2 is about 20 mm. 

 long, with 37 segments, tapering gradually and regularly to a delicate and flagellate 

 tip. The basal segments are broader than long, the eighth is about as long as broad, 

 and those following slowly increase in length so that the terminal are about twice as 

 long as broad. The second-seventh segments have narrow carinate processes with a 

 straight crest which are highest on the fourth and fifth; these give the pinnule the 

 appearance of being broadest at this point and slowly tapering both toward the base 



