MONOGKAPH OF THE EXISTING CEINOIDS. 9 



Diameter of radial pentagon at base, 6.3 mm. ; height of articular face, 2.8 mm. ; 

 width (at transverse ridge), 3.8 mm.: distance from center of rosette to middle of 

 dorsal outer edge of radial, 2.9 mm.: di.stance from center of ventral face of radial 

 pentagon to middle of ventral face of radial, 1.9 mm.; to apex of interradial 

 angle, 2.9 mm. 



CAriLI..\STEK MULTIRADIATA. 



Figs. 7, S. p. 6. 



The articular faces of tlie radials are in general similar to those of C. sentosa. 



The dorsal ligament fossa is somewhat more flattened proximally. The inter- 

 articular ligament fossa? are relatively lower and broader, their maximum height 

 being about equal to that of the dorsal ligament fossa. Their distal edges slope 

 downward from the intermuscular furrow, making a slight angle with the trans- 

 verse ridge. Their maximum height is but very slightly greater than one-half of 

 the distance from the center of the central canal to the end of the transverse ridge. 

 (Iwing to the outward and downward sloping of the distal edges of the interarticu- 

 lar ligament fossae the muscular fossae are narrowly triangular: their greatest trans- 

 verse diameter is about three times their greatest (outer) vertical diameter; their 

 distal border is parallel to the transverse ridge ; and their distal outer angle projects 

 strongly. The interradial space between the articular faces is broader than in 

 C. sentosa, as the outer edge of the interarticular ligament foss» retreats more 

 rapidly basally from the ends of the transverse ridge. The ventral surface of the 

 radial pentagon shows a slightly deeper incision in the radial areas than is seen in 

 C. sentosa. 



Diameter of radial pentagon at base, 4.2 mm.; height of articular face, 

 1.9 mm.; width, at transverse ridge, 2.3 mm.; distance from center of rosette 

 to midtUe of dorsal outer edge of radial, 2 mm. ; distance from center of ventral 

 face of radial pentagon to middle of ventral edge of radial, 1..^ mm.; to apex 

 of interradial angle, 2.2 mm. 



XEMASTER RUBIGINOSA. 

 .See figs. 050, 9.57, pi. 1. 



XEMASTER DISCOIDEA. 

 Figs. 9, 10, p. 6. 



The dorsal ligament fossa is very narrow, about four times as broad as high, 

 witli the proximal border evenl}' curved. The ligament pit is reniform, narrow, 

 rather longer transversely than the greater (transverse) diameter of the oval 

 central canal. 



The transverse ridges of adjacent joint faces are separated from each other 

 interradially ; the interarticular and muscular fossse are separated interradially by 

 a moderatelv wide shallow furrow. 



