LOWER HELDERBERG ROCKS. 107 



PLATE II A. 

 Fig. 1. A large individual, showing the anal or irregular side of the specimen, with nume- 

 rous anal or interbrachial plates, the base of the proboscis, arms, etc. The upper 

 part of the proboscis is covered by adhering stony matter. 



Geological position and locality. In the thin shaly intercalated layers of the 

 Pentamerus limestone : Wheelock's hill, Litchfield, Herkimer county. 



lUaiiacrinus ])acli}dact}Ias. 



Plate III. Fio. 1 - 4 a. 



Adinocriniles pohjdadyltis, Schenectada Reflector, 1835. 



Jistrocriniles pachydaclylus , Conrad in Catalogue, Ann. Rep. on Pal. N. York, 1841, p. 34. 



Jhtrocriniits pachydaclylus, Mather, Geol. Report 1843, p. 246. 



Body broadly turbinate or subhemispherical (the form presented depending 

 much on the degree of pressure it has sustained in the rock). Surface 

 ornamented by strong radiating ridges from the centre of the plates, 

 which, combining, give the whole a reticulate aspect, and each plate a 

 star-like appearance : this character extends not only to the plates of 

 the body, but to the brachial plates, and beyond the bases of the 

 auxiliary arms. Basal plates wider than long, with prominent ridges 

 extending to the upper edges, and a thickened lower margin. First 

 radial or first costal plates as wide as long, four heptagonal and one 

 hexagonal, marked with strong rays near the margin, and a strong ridge 

 through the length of the plate in the direction of the arms. Second 

 radial plates heptagonal, as long as wide, smaller than the first radials, 

 and marked in the same manner. Third radial plates smaller than the 

 second ; three of them heptagonal, the others probably of the same form. 

 Interradial plates small, strongly angulated upon the surface. Brachial 

 plates heptagonal, two upon each third radial, and each succeeded by 

 two other plates, which are slightly divergent and admit between them 

 a row of smaller plates : again bifurcating upon the third brachial plate, 

 the outer plate on each side gives origin to the auxiliary arm, and the 

 two inner ones converge over the intercalated range of smaller plates, 

 giving origin in direct line to the double series of plates which compose 

 the main arm. 



