536 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



spines of proximal adambulacral plates with a modified, more or less 

 truncate, capitate, sometimes papillose lip. 

 6\ Intercostal membrane without tegumentary prickles; costae numerous, 

 close togethei", without intercostal bands of pedicellariae on the proxi- 

 mal half of the costal region ; a costal arch opposite each adambulacral 

 plate. 

 c\ Costae decidedly irregular in the median radial region; costal spinelets 

 equal in length to height of costal ridges, or slightly exceeding same ; 



costae 35 to 50 Craterohrisinga panopla (Fisher). 



c*. Costae regular and parallel in the median radial region, passing directly 

 from one margin to the other ; costal spinelets shorter, less than 

 height of ridges ; costae upward of 80. 



Craterohrisinga parallela (Koehler). 



b\ Intercostal membrane with tegumentary prickles ; intercostal spaces with 



bands of pedicellariae, sometimes inconspicuous ; costal arches usually 



not regularly opposite each adambulacral plate, but variable. 



c*. Rays 9 ; proximal adambulacral plates with only 1 capitate subambu- 



lacral spine, the associated spinule being conspicuously smaller, and 



truncate or bluntly pointed ; suboral spines usually 3, small. 



Crateroltrisinga alberti (Fisher). 



c*. Rays 11 ; proximal adambulacral plates with usually the second sub- 



ambulacral truncate and slightly capitate, and nearly as long as, 



though slenderer than, its companion ; suboral spines 2, large. 



d^. Costae 17 to 20 (in addition to 5 or 6 rudimentary ones at base of 



ray), well spaced, prominent, rather irregular, and occupying about 



the proximal third of ray Craterohrisinga eucoryne (Fisher). 



d*. Costae about 35 (in addition to only 1 or 2 rudimentary ones at base 

 of ray), but last 10 are inconspicuous; costal region occupying 

 about half length of ray ; costae fairly regular and parallel and the 

 proximal ones closer together than in rZ\ 



Craterohrisinga analoga Fisher. 

 6*. Intercostal integument without tegumentary prickles and with conspicu- 

 ous intercostal bands of pedicellariae; costae opposite alternate ambu- 

 lacral plates, hence well spaced ; rays 15 ; costae 30 to 35 ; disk medium, 

 some of its plates with more than 1 spinelet ; suboral spine rather small 

 and delicate; proximal subambulacral spines only slightly modified, 



truncate Craterohrisinga evermanni (Fisher). 



a*. Intercostal integument of most of costal region strengthened by rnnny close- 

 set, contiguous, or overlapping papery plates of conspicuous size, com- 

 pletely filling the interspaces ; proximal subambulacral spines acicular. 

 &\ Costae 35 to 40, beginning at base of ray; no intercostal spinelets, the 

 plates being smooth ; first subambulacral spine pointed. 



Stcgnobrisinga placoderma (Fisher). 

 h*. Costae 18 to 24, the alternate ones complete, and beginning at a conspicu- 

 ous distance from disk, the interval being covered with irregularly dis- 

 posed, spiniferous plates without arches ; intercostal plates beyond this 

 spiniferous basal area without spinelets; first subambulacral spine 

 slightly broadened at tip, the following spines acicular. 



Stcgnobrisinga gracilis (Koehler).* 



^ I am not sure of the generic position of this species, as the gonads and condition of 

 the first adambulacral plates are not known to me. 



