A MONOGllAPH OF THE EXISTING CRINOIDS 237 



(axillaries) are short pentagonal, with the distal angle somewhat produced. The 

 IIBr series are 4 (3 + 4), rather long; the IIBr, are partially in contact. There are 

 no IIIBr series. 



The arms are 16-20 in number, exceedingly slender, appearing very rongli 

 because of the concave surface and somewhat produced distal ends of the brachials. 

 The arms taper uniformly and gradiially from the base. The first 4 or 5 brachials 

 are discoidal, approximately as long as broad. These are followed by some triangidar 

 brachials of moderate length, which after the twelfth to the fourteenth become 

 bluntly wedge-shaped. The length of the brachials remains moderate imtil near 

 the ends of the arms, they not being strongly elongated. The outer brachials are 

 slightly wedge-shaped. In arms arising from a IBr axillary the first 2 brachials are 

 much enlarged and similar to the first 2 elements of a IIBr series. 



In arms arising from a IBr axillary the first syzygy is between brachials 3 + 4, the 

 second is between brachials 6 + 7, and those following occur at intervals of 4 muscular 

 articulations. In arms arising from a IIBr axillary the first syzygy is between 

 brachials 2 + 3, the second is between brachials 5 + 6 to 8 + 9, and those following are 

 separated by usually 4, more rarely 3, muscidar articulations. The sj'zygial pairs 

 are elongated, beyond the middle of the arm being approximately twice as long as a 

 single brachial. 



In the larger 20-armed specimen Pd is about 12 mm. long and is composed of 

 40-50 segments, of which the 3-5 basal are large and strongly broadened and those 

 succeeding much more slender, so that beyond these enlarged basal segments the 

 pinnule appears flagellate. The 2 or 3 lowest segments are slightly carihate. The 

 terminal comb is poorly developed. 



In the smaller 16-armed specimen P^ does not show the strong contrast between 

 the basal and the later segments, and the pinnule tapers gradually outward from the 

 base. One or two of the basal segments are carinate. 



Pi is of the same character as Pd, but in the smaller specimen it is much weaker. 

 The carination of the basal segments is more strongly marked than it is in Pd. 



Pj is very short and is composed of only 10-14 segments, of which the basal 

 are carinate. The terminal comb is either very short or altogether lacking. 



Pj is somewhat longer than P2 and is without any carination of the basal seg- 

 ments; it sometimes shows a trace of a comb. 



The distal pinnules are about 6 mm. long with elongated and centrally con- 

 stricted segments which have produced and spinous distal ends. Only tiie basal 

 segments are short, and these are not remarkable for any special enlargement. 



The disk of the larger specimen is 9 mm. in diameter. In both examples the 

 mouth is strongly excentric, and in both the disk is thickly beset with small conical 

 papillae and calcareous concretions. Between the division series of the smaller 

 specimen there is a pavement of rhombic calcareous plates. In the larger this 

 calcareous covering of the interradial perisome forms a continuous plating, which 

 appears to be composed of small irregularly formed calcareous plates, and the surface 

 is beset \vith conical prominences. 



In color the larger specimen is light brownish white with a longitudinal darker 

 median stripe on the arms. The centrodorsal and the cirri are white. The smaller 



