MONOGRAPH OV THE EXISTING CKINOIDS. 535 



The column, of which the distal part is missing, contains 16 columnals. The 

 first two are very thin, the following gradually increasing in length to the eighth, 

 which, with the following, is about twice as long as broad. All of the columnals 

 show a median annulus, which, though very conspicuous and projecting outward 

 for some distance on the earlier, becomes inconspicuous after the ninth or tenth. 



There are five prominent rounded infrabasals. 



The basals, of the same height as the orals, form a deep and narrow cup, 

 which is about as broad as high. In the outer half of this cup the sides are 

 nearlj^ parallel ; in the proximal half they curve regularly and rather rapidly 

 inward to the top of the column. 



The orals are, broadly speaking, shaped like those of Hathrometra prolixa; 

 in a lateral view of the calyx the distal and lateral profiles of the orals collectively 

 are straight for about half their length, uniting with each other in a broad regular 

 curve; in other words, the orals show an oblong figure, broader than long, with 

 the two outer angles broadly rounded off. In the proximal half of each oral the 

 sides are parallel; the profile of the outer half in direct view is semicircular. A 

 triangular median portion extending from the proximal border as a base to a point 

 about two-thirds of the distance from the base to the tip in the median line as 

 the opposite apex is depressed, taking the form of a spherical triangle. With 

 this portion the remainder makes a slight angle. The median distal region is 

 broadly rounded, neither carinate nor flattened, so that the orals when closed 

 together leave a relatively large stellate opening between their apices. 



There are no radial structures. 



No. 5 (fig. 885. p. 533) : Dredged on February 7. 1903, at a depth of 350 meters. 



This specimen resembles the preceding, and similarly there is no notch in the 

 distal border of the orals. 



No. 6 (fig. 886, p. 533) : Dredged on January 28, 1903, at a depth of 380 meters. 



Total length, 2.3 mm.; length of crown, 0.3 mm. 



The column consists of 16 columnals and a terminal stem plate; the topmost 

 columnal is very short and discoidal, the following increasing in length to the 

 sixth, which is about as long as broad, and the seventh, which is about twice as 

 long as broad, still further increasing to the ninth-eleventh, which are about 

 six times as long as broad, and from that point decreasing in length distally. A 

 narrow median girdle is visible in all the columnals and projects strongly in the 

 first six ; in the seventh it passes about the end of the proximal third. 



The terminal stem plate is regularly and broadly pentalobate. 



Infrabasals of considerable size appear to be present. 



The basal ring is of moderate proportions, half again as broad distally as high. 



Five minute radials appear to be present. 



Just to the left of and on the same level as one of these is a much larger 

 plate, the radianal. 



The orals have approximately parallel sides in the proximal half; in the 

 distal half they are bent inward, and the sides converge to a rounded distal angle. 

 Each is roughly divided into thre« triangular and one rhombic areas. Bounded 

 142140— -21— Bull. 82 36 



