MONOGRAPH OF THE EXISTING CRINOIDS. 



77 



i'. The muscular and interartlcular ligament fossse lie in the same plane; the 

 outer distal angles of the interartlcular ligament fosste are at a height 

 much less than one third of the distance between the inner proximal and 

 distal angles of the muscular fossje: the eentrodorsal is rounded, and the 

 cirrus sockets are irregularly placed ; the radial areas are not difEer- 

 entiated. 

 f. The distance from the proximal border of the transverse ridge to the 

 proximal border of the dorsal ligament fossa is about equal to one- 

 third of the distance from the former to the distal border of the mus- 

 cular fossfe Goccometra hagenii. 



f. The distance from the proximal border of the transverse ridge to the 

 proximal border of the dorsal ligament fossa is much less than one-third 

 the distance from the former to the distal border of the muscular fossse. 



Leptometra. 

 h'. The muscular fossre are lower and broader, usually much less than twice as 

 high as the maximum width, 

 r. The distal borders of the interartlcular ligament fossiB are straight and 



parallel to the transverse ridge Solanometra antarctica. 



i'. The distal borders of the interartlcular ligament fossfe are directed more or 

 less upward and outward. 

 )'. The ridge forming the distal border of the interartlcular ligament fossK 

 does not reach the outer border of the joint face, which makes an un- 

 interrupted curve. 

 k\ The distal borders of the interartlcular ligament fossse make an angle 

 of about 60° with the transverse ridge; the tips of the muscular fossae 



are abruptly swollen Uanometra towcrsi. 



k'. The distal borders of the interartlcular ligament fo.ssse make an angle of 

 about 30° with the transverse ridge; the tips of the muscular fossie 



are not abruptly swollen Hathrometra proUxa. 



;'. The ridge forming the distal border of the interartlcular ligament fossae 

 reaches the outer border of the joint face where it causes an interrup- 

 tion of the continuity. 

 fc\ The outer portion of the muscular fossie is constricted. 



Triohometra cubensis. 

 A-'. The outer border of the muscular fossse is regularly convex. 



f. Ten radlals Promachocrinus kerguelensis. 



}-. Five radlals. 



hi'. The muscular fossae are very broad and broadly rounded, rounded 

 trapezoidal in shape; their planes make a relatively small angle 

 with the dorsoventral axis so that the central space between the 

 radials is very large, the diameter of the circle delimited by the 

 ends of the muscular fossae being nearly one-half the diameter of 



the radial pentagon Psathyrometra fragilis. 



^)l^ The muscular fossic are narrower and less broadly rounded, 

 rounded triangular in shape ; their planes make a larger angle with 

 the dorsoventral axis so that the diameter of the circle delimited 

 by the ends of the muscular fossae is never more than one-third 

 the diameter of the radial pentagon and is usually much less. 

 n\ The diameter of the circle delimited by the distal ends of the 

 muscular fossae is about one-third that of the radial pentagon. 



Hcliometra glncialis. 



n'. The diameter of the circle delimited by the distal ends of the 



muscular fossse is about one-fifth that of the radial pentagon. 



Hathrometra teneUn. 



