26 



ACTINOCRINUS PALLUBRUM, n. Sp. 



Plate I, Fig. 25, basal view; Fig. 26, summit view; Fig. 27, 



azygous side. 



Species medium size, somewhat lenticular, though the calyx 

 is larger than the vault. Calyx basin- shaped, two and a half 

 times as wide as high. No radial ridges. Plates thick, tumid 

 and sculptured, so as to be more or less pyramidal. Ambula- 

 cral openings directed upward and not visible in a basal view. 



Basals form an hexagonal disc with slight re-entering angles, 

 having an hemispherical depression for the attachment of the 

 column, and a diameter about one-half more than the diameter 

 of the column. First primary radials rather larger than any 

 other plates, in the body, three hexagonal and two heptagonal. 

 Second primary radials about two-thirds as large as the first 

 and hexagonal. Third primary radials about the size of the 

 second, pentagonal, axillary, and support on each upper slop- 

 ing side a single secondary radial, about the size of a third 

 primary radial, which is axillary and bears upon each upper 

 sloping side a single tertiary radial, which arrangement gives 

 to this species twenty arms and twenty ambulacral openings 

 to the vault. 



All of the interradial and intersecondary radial areas connect 

 with the vault. In the regular interradial areas there is one 

 plate in the first range, two in the second, two in the third, 

 and, in some of the areas, one m the fourth range that con- 

 nects with the plates of the vault. In other cases there are 

 two plates in the fourth range. There are, therefore, six plates 

 in some of the regular areas, and seven plates in other areas. 

 There is a single plate in each intersecondary radial area, and 

 it connects with the plates of the vault. In the azygous area 

 there are fifteen plates. The first plate is in line with the first 

 primary radials, and nearly as large. It is followed by three 

 plates in the second range and four plates in the third range, 

 one of which extends as high as the top of the fourth range. 

 In the fourth range there are two plates, and two in the fifth 

 range, and two in the sixth range, both of which connect with 

 the plates of the vault. 



The vault is only moderately convex, and is covered with 

 numerous small, polygonal plates. The smaller plates are con- 

 vex and the larger ones subspinous. 



