MONOGRAPH OF THE EXISTING CRINOIDS. 71 



fc'. The muscular fossfc extend Inward for some distance around the inner 



dlstai angles of the interarticular ligament fossse and down along 



their inner borders. 



?. The outer portions of the interarticular ligament fossse are separated 



Interiorly by a space approximately equal to their own width and 



the muscular fossae are very widely separated interiorly. 



Comaster fruticosus. 

 V. The outer portions of the interarticular ligament fossfe are separated 

 by a space equal to less than half their own width and the inner 

 edges of the muscular fossfe are almost in contact. 



Comatula pectinata. 



k'. The muscular fossse do not extend inward beyond the inner distal angles 



of the Interarticular ligament fossse. 



P. The inner borders of the interarticular ligament fossfe are S-shaped, 



so that the space between them is broadest proximally becoming 



much narrower distally between their imier distal angles. 



Capillaster sentosa. 

 ?. The inner borders of the interarticular ligament fossse are approxi- 

 mately parallel. 

 ni'. The distal portion of the outer borders of the interarticular liga- 

 ment fosssie is strongly concave, so that the muscular fossie extend 



outward for some distance beyond them Comatella maculata. 



m\ The outer borders of the interarticular ligament fossee are approxi- 

 mately straight. 

 n.\ The outer borders of the m\iscular fossaa slant upward and out- 

 ward, so that a more or less pointed distal outer angle results. 



Comatula micraster. 

 n'. The outer borders of the muscular fossae are straight and per- 

 pendicular to the transverse ridge, or evenly convex, the chord 

 of the convexity being perpendicular to the transverse ridge. 



Comactinia echinoptera. 

 f. The interarticular ligament fossse are not so high as their minimum width. 

 fc^ Interarticular ligament fossse more than twice as broad as high. 



Nemaster discoidea. 



k'. Interarticular ligament fossse much less than twice as broad as high. 



?. The outer borders of the interarticular ligament fossre are markedly 



convergent, so that the articular faces of the radials beyond the 



transverse ridge are separated by a comparatively wide V-shaped 



gap Comaster parvus. 



I'. The outer borders of the interarticular ligament fosste are more nearly 

 parallel, so that the articular faces beyond the transverse ridge are 

 separated by a vary uarrow V. or by a parallel-sided furrow. 

 to'. The muscular fossse are slightly S-shaped, the inner half convex, 

 the outer half concave and curving upward and outward. 



Nemaster rubiginosa. 

 m'. The muscular fossse are uniformly convex. 

 n\ The muscular fossa; are very strongly convex, the distal borders 

 of the interarticular ligament foss.e being very strongly bowed 



outward Comatula rotalaria. 



7t^ The muscular fossse are only slightly convex, the distal borders of 

 the interarticular ligament fossre being almost straight. 



DJeocom,atella pulchclla. 

 142140— 21— Bull. S2 7 



