60 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



Diameter of radial pentagon at base, 7 mm.; lieight of articular face (meas- 

 ured along the inclination), 4 mm.; width, at transverse ridge, 3.7 mm.; distance 

 from center of rosette to middle of dorsal outer edge of radial, 3 mm. ; diameter of 

 ventral interarticular space. 1.9 mm. 



FLOROMETRA PERPLEX.\. 

 Fig,s. 95, OG, p. 62, and 1009-1014, pi. 5. 



In general the radial articxdar faces in this species resemble those of 

 F. asperHTna. The central calcareous structures, however, are much larger, their 

 base occupying a distance along the transverse ridge equal to one-half the entire 

 length of the ridge. The central portion of these structures is roughly oblong, 

 half again as broad as high, with the distal angles produced outward and slightly 

 upward. On account of the large size of these central structures the interarticular 

 ligament fossae are much restricted, and do not extend inward more than halfway 

 to the median axis of the joint face. The proximal border of the interarticular 

 ligament fossae is more evenly curved than in F. asperrhna. There is a slight 

 development of calcareous matter within the ventral cavity of the radial pentagon. 



Diameter of radial pentagon .at base, 6 mm. ; height of articular face (meas- 

 ured along the inclination), 3.4 mm.; width, at transverse ridge. 3 mm.; distance 

 from center of rosette to middle of dorsal outer edge of radial, 2.6 mm.; diameter 

 of ventral interarticidar space, 1.6 mm. 



riiOROMETRA TANNERI, 

 Pig. 1008, pi. 5. 



Zenometrin^. 



The articular faces of the radials are about one-third again as high as broad. 

 The interarticular ligament fossae are inclined inward at an angle of from 60° to 

 80°, but the muscular fossae are nearly or quite parallel with the dorsoventral axis 

 of the animal. The inclination of the dorsal ligament fossa is intermediate between 

 that of the interarticular ligament and the muscular fossae. 



The interarticular ligament fossae are about as high as the well-rounded dorsal 

 ligament fossa, but less than one-half as high as the muscular fossae. Their distal 

 borders make an angle of about 4.5° with the transverse ridge, at least inwardly. 

 The outer portion may curve about so as to become nearly or quite horizontal (that 

 is, parallel to the transverse ridge). 



The muscular fossae are narrow or broad, according to the angle made by the 

 interarticular ligament fossae witli the dorsoventral axis; they are well rounded, 

 everywhere convex, their rounded lateral edges projecting considerably beyond the 

 straight or slightly convex ends of the interarticular ligament fossas. 



The muscular fossae are separated interiorly by a high but rather narrow inter- 

 muscular septum, and distal to it by a wide intermuscular notch, broadly rounded 



