4 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



scriptions taken from these figures in the text on account of the possibility of error 

 in the drawings; and for the same reason I have refrained from making com- 

 parisons between these and the drawings made by Miss Dandridge under my 

 supervision. 



COMASTERID^}. 



The articular faces of the radials lie in planes nearly or quite parallel to the 

 dorsoventral axis of the animal. 



The excavation of the various elements of the joint face is very slight. 



Just ventral to the transverse ridge there is a broad flat area, narrow laterally 

 but centrally increasing in height so as to encompass the central canal; anteriorly 

 this sinks almost imperceptibly into the interarticular ligament fossae. 



The elements of the joint face on either side of the transverse ridge are usually 

 on the same plane, but the dorsal ligament fossa sometimes makes a slightly 

 greater or lesser angle with the dorsoventral axis than the distal elements. 



The dorsal ligament fossa is almost always lower than the interarticular liga- 

 ment fossae, and its proximal border is more or less flattened; the ligament pit 

 is strongly marked, broadly oval, larger than the central canal. 



The central canal is broadly oval and rather small. 



The joint face elements distal to the transverse ridge and the central canal 

 are separated by a broad and shallow intermuscular furrow which is usually con- 

 stricted between the muscular fossse. 



The distal border of the interarticular ligament fossae is straight, or slightly 

 convex : it is commonly parallel to the transverse ridge, but it may be slightly 

 lower interiorly than exteriorly; more commonly it is slightly lower exteriorly 

 than interiorly. 



The muscular fossae are small, always smaller than the interarticular liga- 

 ment fossse (usually less than half the height of these), transversely elongate 

 with nearly or quite parallel distal and proximal edges and a projecting distal 

 outer angle; the distal edge is horizontal, or, if it is somewhat convex, the chord 

 of the convexity is horizontal. 



The ventral face of the radial pentagon as a whole is bluntly stellate, the 

 radial incisions being usually less than one-third, never more than one-half, 

 of the distance from the center to the interradial apices. 



The ventral plug is well developed, with a flat or slightly concave surface 

 which is nearly or quite on a level with the distal edge of the muscular fossae; 

 it almost or quite conceals the inner surface of the radials. The radial canals 

 are very broad ; there is no free central canal. 



CAFILLASTERINJE. 



The following features appear to be characteristic of the radial articular 

 faces of the species of Capillasterinse. 



The interarticular ligament fossae are much broader than high. 



The distal border of the interarticular ligament fossae is usually lower ex- 

 teriorly than interiorly. 



