MONOGRAPH OF THE EXISTING CRINOIDS. 37 



tance from center of rosette to middle of dorsal outer edge of radial, 2.7 mm. ; 

 distance from center of ventral surface of radial pentagon to middle of ventral 

 outer edge of radial, 1.3 mm. ; to apex of interradial angle, 1.8 mm. 



CTLLOIIETRA ALBOrURPUREA. 



Figs. 54, 55. p. 33. 



The radial articular faces up to the proximal borders of the muscular fossae 

 lie in the same plane, which is inclined at an angle of nearly 4.5° to the dorsoventral 

 axis of the animal. The muscular fossae, forming an obtuse angle with the remain- 

 ing elements of the joint face, are parallel to the dorsoventral axis. The radial 

 faces are entirely separated interradially by a uniform narrow V-shaped groove. 



The dorsal ligament fossse are moderate in size, about two and one-half times 

 as broad as long. The proximal border is uniformly convex and turns up rather 

 abruptly at the ends. 



The interarticular ligament fossfp are equilateral triangles, but their inner 

 angles are rather broadly truncated by the prominent rim of the central canal. 



The muscular fossse are trapezoidal in shape, with the distal angles rounded 

 off. The lateral edges beyond the interarticular ligament fossae are equal in length 

 to the distal edges and are at right angles to them; the inner edges are nearly twice 

 as long, running down to the ridge about the central canal upon which the apices 

 of the trapezia abut. 



The muscular fossaj are separated interiorly by a narrow rounded ridge, at 

 first as high as the rim about the central canal, but gradually decreasing in height 

 and distally dying away altogether. 



The interior of the radial pentagon is filled with a spongy calcareous mass 

 which reaches to the level of tlie distal edges of the muscular fossa; through which 

 there is a rather small central channel. 



Diameter of radial pentagon at base. 3 mm. ; height of articular face (measured 

 along the inclination), 1.7 mm.; width, at transverse ridge, 1.3 mm. 



CTLLOMETRA DISCIFORMIS.^ 

 See figs. 9G0. 970, ij1. 2. 



OLIGOMETRA SERRIPINXA. 



1-Mgs. 58, 50, II. .S3. 



The dorsal ligament fossa is rather narrow, about tliree times as broad as liigh, 

 with the proximal border strongly flattened but strongly curved upward at the 

 ends. The ligament pit is almost semicircular, about half as large as the trans- 

 versely oval central canal. 



In the interradial angles the ends of the transverse ridges are well separated 

 and the dorsal ligament fossa; are very widely separated. The elements of the 

 joint faces distal to the transverse ridges are separated by a rather deep inter- 



