46 



ACTINOCRINUS AI.BERSI, tl. Sp. 



Plate II, Fig. 21, azygous side; Fig. 22, apposite view; Fig. 23, 



summit view. 



Species medium or above medium size. Calyx obconoidal, 

 from one-third to one-half wider than high; plates convex and 

 the larger ones sculptured so as to be more or less pyramidal, 

 angles slightly depressed. No radial ridges. Column medium 

 .size. 



Basals very short and project almost their entire length be- 

 low the end of tlie column. They are beveled at the sutures 

 so as to give the base a subhexagonal outline. The cicatrix 

 for the attachment of the column is nearly or quite flat. First 

 radials wider tlian long, three hexagonal, and two heptagonal, 

 widening from the base to the lateral angles and contracting 

 above. Second radials from one-fourth to one-half .smaller 

 than the first, hexagonal, and wider than high. Third primary 

 radials a little smaller than the second, pentagonal, axillary, 

 and support on each upper sloping side a single secondary ra- 

 dial, which is axillary, and, in three of the rays, sujjport on 

 eaqh upper sloping side a tertiary radial, which gives to each 

 of these rays four arms. In each ray adjoining the azygous 

 area, there is, on the distal side of each third jirimary radial, 

 a secondai'y radial, that supports upon each upper sloping 

 side a single tertiary radial; but the secondary radial on the 

 proximal side of the third primary radial bears upon its distal 

 side an axillary tertiary radial, that bears upon each upper 

 sloping side a quarternary radial, and ujaon its proximal side 

 two tertiai'y radials, which gives to each of these two rays 

 five arms. There ai-e, thei-efore, twenty- two ambulacral open- 

 ings to the vault, in this species. 



The regular interradial areas do not connect with tlio ]>lates 

 of the vault. In each of three of tlie areas there are five 

 plates, one, followed by two in the second range and two in 

 the thh-d range; but in the other area there are six jjlates, 

 one, followed by two in the second range, and two in the tliird 

 range, and one small ])late, in the fourth range. We do not 

 suppose, however, that this slight dilference, in the interra- 

 dial areas, is of specific importance, and de.scribe it only be- 

 cause our specimen is so constructed. The azygous area con- 



