40 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



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

 along the inclination), 2.5 mm.; width, at transverse ridge, 3.7 mm.; distance from 

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

 center of ventral face of radial pentagon to middle of ventral edge of radial. 

 0.8 mm. ; to apex of interradial angle, 2.5 mm. 



TROPIOM ETItA I'ICTA. 

 Figs. 62, 63, p. 33. 



TROPIOMETRA CARTNATA. 

 Figs. 971, 972, pi. 2. 



CALOMETRID^E. 



The articular faces of the radials are approximately crescentic and are entirely 

 separated from each other as in Comatilia. 



The dorsal ligament fossa is nearly semicircular. 



The interarticular ligament fossae have the distal border deeply concave, par- 

 allel to the distal border of the joint face; the outer borders are about as high as 

 the median height of the dorsal ligament fossa. 



The muscular fossse are very narrow, about as broad as the dorsoventral 

 diameter of the central canal, forming a band-like border along the distal edges 

 of the interarticular ligament fossse. 



The ventral surface of the radial pentagon is very widely open ; there is a 

 small central plug in the middle. 



NEOMETRA MULTICOLOR. 

 Figs. 65, 66, p. 43. 



The radial faces are approximately crescentic; the outer (dorsal) edge forms 

 almost a semicircle, while the inner (ventral) border is strongly and evenly con- 

 cave, the concavity in the median line reaching almost down to the central canal. 

 The plane of the radial faces makes only a very slight angle with the dorsoventral 

 axis. The radial faces are entirely and rather widely separated by a bare, slightly 

 hollowed interradial area, which is rounded and sometimes more or less spatulate 

 distally. The radials are in unusually close apposition, so that the suture between 

 them is rarely visible. 



The dorsal ligament fossa is about two and one-half times as broad as long. 

 The proximal edge is evenly curved, and its curve is regularly continued anteriorly. 



The central canal is more flattened than usual, being elliptical and about twice 

 as broad as long. It is bordered laterally and distally by a narrow, low, and more 

 or less inconspicuous ridge. 



The distal border of the interarticular ligament fossse is narrow, low, and incon- 

 spicuous; arising from a point on either side of the median distal portion of the 

 ventrolateral ridge about the central canal it runs outward, deeply concave and 



