10 



Found in the St. Louis Group, in Hardin county, Kentucky, 

 and now in the private collection of Wm. F. E. Gurley. 



CLASS CRINOIDEA. 

 ORDER P AL AEOCRINOI DE A . 

 FAMILY ACTINOCRINID.E. 



ACTINOCRINUS GIBSONI, n. Sp. 



Plate 2, fig. 1, dorsal, or opposite view irom the azygous side. 



Species very robust: column, calyx, and arms large. Our speci- 

 men is compressed, but evidently the calyx is quite as long as 

 wide, deeply sculptured, plates thick, and interradial areas 

 rather small. Proboscis unknown, but another specimen, prob- 

 ably belonging to this species, has a moderately long proboscis 

 curved to one side toward the top, and is covered with tumid 

 plates like an Eretmocrinus. Column composed of thicker and 

 thinner plates, the former projecting beyond the latter. 



Basals one half wider than high, very thick, contracted in the 

 middle so as to leave an expanded rim projecting much beyond 

 the column and widely gaping at the sutures in the rim, the 

 excavation being almost triangular and extending nearly to the 

 radial plates; upper part of the plates having three short, longi- 

 tudinal ridges that fade away before reaching half the length of 

 the plates. 



First primary radials very large, nearly half as long as the 

 calyx, one-third longer than wide, three hexagonal, two hep- 

 tagonal ; the surface is marked with a strong transverse tubercle 

 in the middle part, from which the heptagonal plates have two 

 radiating ridges extending to each of the adjoining basals and 

 one toward each of the other adjoining plates; and the hexag- 

 onal plates have three ridges extending to the single abutting 

 basal and one toward each of the other adjoining plates; each 

 plate also bears a small, round tubercle above the transverse 

 one. Second primary radials less than half the size of the first; 

 hexagonal superior sloping sides shorter than the inferior ; sur- 

 face ornamented with a high pointed tubercle and a rounded 

 radiating ridge directed toward each adjoining plate. Third 

 primary radials smaller than the second ; heptagonal, orna- 

 mented in the same way that the second are, and bearing upon 



