MONOGRAPH OF THE EXISTING CKINOIDS. 7 



outer edge of radial, 3.8 mm. ; distance from center of ventral face of radial 

 pentagon to middle of ventral outer edge of radial, 3 mm. ; to angle between radials, 

 4.8 mm. 



COMATELLA STELLJGERA. 

 See figs. 950-952, pi. 1. 



COMATELLA MACTTLATA. 



See figs. 953, 954, pi. 1. 



NEOCOMATELLA PTJLCHELLA. 

 Figs. 3, 4, p. 6, and 955, pi. 1. 



The dorsal ligament fossa is narrow, about four times as broad as long, some- 

 what blunted at the lateral angles ; the lateral edges of the interarticular ligament 

 fossae may retreat at first rather rapidly from the transverse ridge, but, gradually 

 curving, at the distal corner these edges make only a small angle with a line perpen- 

 dicular to the ventral surface of the centrodorsal, or they may be only slightly 

 concave. 



The interarticular ligament fossae are squarish to nearly one-third broader than 

 long, with the distal edge turned outward, horizontal, slightly and evenly convex, 

 or sloping slightly downward from a point about one-third of the distance from 

 the inner corner. The inner corner is broadly rounded so that the inner edges are 

 parallel, about as far apart as the diameter of the central canal. Just before or 

 just after the consummation of the curve of the inner distal angle the projection 

 of the distal edge rather suddenly disappears, so that the inner lateral edges are 

 scarcely raised above the general surface of the broad shallow groove which sep- 

 arates them. 



The muscular fossae are approximately twice as broad as high. They are sep- 

 arated basally by the continuation of the broad shallow groove which separates 

 inwardly the interarticular ligament fossse. The floor of this groove, at first flat, 

 at about the middle of the interarticular ligament fossae begins to be slightly con- 

 vex, and where it passes between the muscular fossae to the ventral surface of the 

 radials, gradually curving so as to become parallel with the latter, it may become 

 carinate and bear a few long spicules. It leaves the plane of the radial face and 

 begins to curve downward (in reference to the latter) at about the middle of the 

 inner edges of the muscular fossae; because of its gradual curve at first the exact 

 spot is somewhat difficult of determination. The outer edge of the muscular fossae 

 is usually a straight line, but may be slightly concave. It usually makes about the 

 same angle with a line perpendicular to the centrodorsal as that made by the outer 

 edge of the interarticular ligament fossae, but reversed, so that it projects outward 

 making an obtuse angle with the outer edge of those fossae; the outer edge of the 

 muscular fossae is about one-half to two-thirds as long as that of the interarticular 

 ligament fossae. The muscular fossae as a whole are usually from two-thirds to three- 

 fourths of the height of the interarticular ligament fossae, usually twice as broad 

 142140 21 Bull. 82 3 



