16 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



Diameter of radial pentagon at base, 4.7 mm. ; height of articular face, 2.3 

 mm. ; width, at transverse ridge, 2.9 mm. ; distance from center of rosette to 

 middle of dorsal outer edge of radial, 1.9 mm.: distance from center of ventral 

 face of radial pentagon to middle of ventral edge of radial, 1.3 mm.; to apex 

 of interradial angle, 2.2 mm. 



Another specimen measures : Diameter of radial pentagon at base, 3.8 mm. ; 

 height of articular face (measured along the inclination), 1.7 mm.; width, at 

 transverse ridge, 2.3 mm. ; distance from center of rosette to middle of dorsal 

 outer edge of radial, 1.6 mm. ; distance from center of ventral face of radial 

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

 angle, 1.5 mm. 



COMACTINIA MERIDIONALIS. 

 See figs. 063, 0(54, pi. 1. 



The interarticular ligament fossae are nearly or quite as high as, or even higher 

 than, broad. 



The distal edges of the interarticular ligament fossae are horizontal, or are 

 somewhat higher exteriorly than interiorly. 



There is no change in direction between the interarticular ligament fossae and 

 the muscular fossae. 



The inner ends of the muscular fossae are inserted well within the inner distal 

 angles of the interarticular ligament fossae. 



In general the muscular fossae have their proximal and distal edges parallel, 

 and lie horizontally. 



In addition to these characters the centrodorsal usually bears no cirri, or is 

 equipped with several rows. If there is only a single row it is irregular and more 

 or less irregularly deficient. 



COMASTER FRtrricostrs. 

 Figs. 21, 22, p. 15. 



The radial articular faces lie in planes parallel to the dorsoventral axis of the 

 animal. The sculpturing is comparatively slight, there being but very little exca- 

 vation in the dorsal ligament fossa. 



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

 with the proximal edge straight and parallel to the transverse ridge for most of its 

 length, at either end curving rather abruptly upward to the ends of the trans- 

 verse ridge. 



The dorsal ligament fossae are entirely separated from each other, but the 

 transverse ridges, which are narrow and stand out prominently, may be more or 

 less united with their neighbors. 



There is no rim about the central canal. 



Shortly beyond the apposed ends of the transverse ridges the lateral borders of 

 the interarticular ligament fossae diverge somewhat, soon becoming parallel again, 



