MONOGRAPH OF THE EXISTING CRINOIDS. 



539 



Just to the left of the smallest radial is the much larger oval radianal, to 

 make room for which the right distal angle of the posterior basal is cut away. 

 Distally and to the left the radianal overlaps the right proximal angle of the 

 posterior oral. 



The orals are rather broad, their sides converging rather rapidly in the 

 distal half to the rounded apex. A triangular area extending from a point about 

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

 to the two proximal angles, so that the proximal border serves as a base, is de- 

 pressed. The portion anterior to this region is exteriorly broadly concave; the 

 lateral portion of the orals is turned outward. Thus the orals of this specimen, 

 instead of being of the form most characteristic of this species (as illustrated in 

 Nos. 6, 7, 8, 9, and 11) tend to approach the form characteristic of the orals of 

 Hathronietra prolixa. 



No. 13 (fig. 892, p. 5331 : Dredged on December 26, 1902, at a depth of 385 meters. 



One specimen resembling the preceding but with the orals, though much 

 broader, essentially like those of No. 2. 



No. 14 (fig. 893, p. 533) : Dredged on January 12, 1903, in 380 meters. 



Total length (distal portion of column missing), 1.3 mm.; length of crown, 

 0.4 mm. 



The fragment of the column attached to the crown consists of 7 segments. 



There appear to be five infrabasals of considerable size. 



The basals form a cup with slightly convex sides which is half again as broad 

 as high. 



The minute beginnings of radials have appeared in the angles between the 

 basals and the orals ; to the left of one of the radials is the larger radianal. 



The orals are rather broad ; their sides are approximately parallel in the 

 proximal half, in the distal half curving broadly inward and converging to a 

 rounded apex. A triangular portion reaching from the proximal border to the 

 middle of the median line is more or less flattened and depressed; the distal por- 

 tion, including the tip and forming a rhombic area the proximal angle of which 

 coincides with the distal apex of the proximal triangle, is also flattened ; the lateral 

 portions not included in these two areas are bent outward (backward). 



No. 15 : Dredged on December 26, 1902, at a depth of 385 meters. 



Total length, 7.8 mm. ; length of crown, 0.7 mm. 



The column consists of 26 columnals and a terminal stem plate. The first 

 three columnals are short and discoidal, with an evenly and sharply rounded 

 lateral profile. The fourth is half again as broad as long, with a narrow pro- 

 jecting girdle just under the proximal border. The following rapidly increase in 

 length to the eighth, which is about three times as long as broad, and the thir- 

 teenth-sixteenth, which are about five times as long as broad. The remainder 

 gradually decrease in length. A narrow median girdle is evident on all the seg- 

 ments; on the earlier it projects beyond the general surface and is very conspicuous, 

 but after the eighth it becomes inconspicuous. Except for the proximal, the 

 columnals are regularly cylindrical without expanded ends. 



The terminal stem plate is slightly lobate. 



