58 BULLETIN 82, UNITED STATES NATIONAL MUSEUM. 



There is more or less of a calcareous deposit within the ventral surface of the 

 radial pentagon, but it is scarcely sufficient to conceal the rosette from ventral view. 



Diameter of radial pentagon, 1.4 mm.; height of articular face (measured 

 along the inclination), 0.7 mm.; width, at transverse ridge, 0.7 mm.; distance from 

 center of rosette to middle of outer dorsal edge of radial, 0.6 mm.; diameter of 

 ventral interarticular space, 0.7 mm. 



Heliometrin.e. 



The articular faces are usually about as high as broad, or somewhat (never 

 over one- fourth) higher than broad. 



The interarticular ligament and the muscular fossae usually make approxi- 

 mately the same angle with the dorsoventral plane of the radial, but the latter 

 may be more nearly parallel with the dorsoventral axis than the former, in which 

 case the inclination of the dorsal ligament fossa in reference to the dorsoventral 

 axis is intermediate between the two. 



The interarticular ligament fossa? are about as high as the well-rounded or 

 subtriangular dorsal ligament fossa, and about half as high as the muscular fossa?. 

 Their outer border is usually more or less strongly concave; their distal border 

 usually makes an angle of from 30° to 45° with the transverse ridge, at least 

 inwardly; outwardly it may become horizontal. 



The muscular fossae are usually rounded triangular, though their sides may 

 be more or less parallel, at least proximally. Their distal angle is usually broadly 

 rounded, but its outer side may be more or less flattened. 



The muscular fossae are separated interiorly by an intermuscular septum which 

 is usually high proximally but rather low for most of its length. It is commonly 

 very narrow but may be considerably broadened in correlation with a general 

 broadening of all the central calcareous structures, especially the inner ends of 

 the distal border of the interarticular ligament fossae. Distally the muscular 

 fossae are separated by an intermuscular notch which is narrow and sharp pointed 

 proximally if the intermuscular septum is narrow, but proportionately broad and 

 rounded proximally if the intermuscular furrow is broad. 



The central canal is large, circular to broadly oval in shape; the ligament 

 pit is large, considerably larger than the central canal, but only slightly marked. 



PROMACHOCRINUS KEEGUELENSIS. 



See figs. 1001, 1002, pi. 4. 



SOLANOMETRA ANTARCTICA. 



See figs. 09T. 098. pi. 4. 



FLOROMETRA ASPERRIMA. 



Figs. 97, 98, p. 02. 



The dorsal ligament fossa is narrow, rounded triangular, three or four times as 

 broad as high. The ligament pit is about twice as broad as the central canal, 

 reniform, but only faintly marked. 



