8 



ACTINOCRINUS BISCHOFFI, n. Sp. 



Plate III, Fig. 1, azygous side; Fig. 2, opposite view; some of 

 the plates around the arm openings are broken. 



Species large. Calyx obconoidal, about as long as wide, ab- 

 ruptly spreading near the arm openings, which are directed up- 

 ward, and are not visible in a basal view. Truncated only the 

 diameter of the column. Plates plain or slightly convex. Sutures 

 beveled; no radial ridges. 



Basals form a cup about two and a half times as wide as high, 

 and which is moderately constricted in the middle part. First 

 primary radials as long as wide, three hexagonal, two heptagonal. 

 Second primary radials about half as large as the first, hexagonal, 

 and a little wider than long. Third primary radials smaller than 

 the second, the one opposite azygous area heptagonal, three hexa- 

 gonal and one pentagonal, axillary, and support on each upper 

 side a secondary radial, which is axillary and supports, on each 

 of the distal sides, four tertiary radials, and upon each of the 

 proximal sides an axillary tertiary radial, which supports, on each 

 upper side two or three quaternary radials, which arrangement 

 gives to each of the rays six arms. There are, therefore, thirty 

 ambulacral openings to the vault in this species. 



None of the interradial areas connect with the vault. In each 

 of three of the regular interradial areas there are seven plates, 

 one, followed by two, in the second range, two in the third range, 

 and two in the fourth range, which are below the tertiary radials. 

 In the other area there are eight plates, the additional one being 

 in the fifth range. There is a small intersecondary plate in the 

 ray opposite the azygous area. There are thirteen plates in the 

 azygous area. The first one is in line with the first primary ra- 

 dials and of the same size. It is followed by three plates, in the 

 second range, four plates in the third range, three in the fourth 

 range, one in the fifth range, and one in the sixth range. The 

 last plate is small and below the union of the last two tertiary 

 radials, in the adjoining radial series. 



The vault is highly convex and covered with small, convex, 

 polygonal plates. It bears a subcentral proboscis. The arm 

 openings are directed upward and visible in a summit view. No 

 ovarian pores have been discovered. 



