12 



ACTINOCRINUS SUBSCITULUS, n. sp. 



Plate III, Fig. 6, azygous side; Fig. 7, opposite view; Fig. 8, 



summit. 



Species above medium size. Calyx obpyramidal, nearly as long 

 as wide, truncated only the size of the column, most rapidly 

 spreading near the free arms. Radial ridges well defined above 

 the first primary radials. Icterradial areas concave and depressed 

 between the arms where the plates unite with those of the vault. 

 Ambulacral openings directed upward and not visible in a basal 

 view. Plates slightly convex. Surface granular. 



Basals form a cup about twice as wide as high, and which is 

 much constricted in the middle part. First primary radials longer 

 than wide, three hexagonal, two heptagonal. Second primary rad- 

 ials less than half as large as the first, hexagonal, wider than 

 long. Third primary radials about the size of the second, three 

 heptagonal, two hexagonal, axillary, and support on each upper 

 sloping side a single secondary radial, which is axillary, and in 

 each of four of the lays support on each upper sloping side two 

 tertiary radials, which gives to each of these rays four arms. In 

 one of the lateral rays, the third primary radial supports, upon 

 one side, an axillary, secondary radial, which supports upon each 

 upper side two tertiary radials, and, upon the other side, a sec- 

 ondary radial that supports, on the distal side, two tertiary radials, 

 and, upon the proximal side, an axillary tertiary radial, which 

 bears upon each upper sloping side a quaternary radial, which 

 arrangement gives to this ray five arms. There are, therefore, 

 twenty-one arms in this species. The arm formula is 4+5+4+4-|-4. 



The regular interradial areas connect with the vault, but they 

 differ widely from each other. In one area there are eleven plates, 

 in another ten, in another nine and in the other eight. Figure 7 

 shows one area with eight plates and the other with eleven plates. 

 The azygous area is wide, flattened, and contains thirteen plates. 

 The first plate is in line with the first primary radials, and of the 

 same size. It is followed, in the second range, by two plates; in 

 the third range, by five plates; in the fourth range, by four plates, 

 and, in the fifth range, by one plate, that unites with the plates 

 of the vault. 



