WHiTEAVES.] FOSSILS OF HAMILTON FORJLATION OF ONTARIO. 95 



his >pecies, like all others of the genus, has not only three or more 

 primary but aUo several secondary radials, connected laterally by inter- 

 radiaU, though these latter, which were moveable in the animal, are 

 rarely preserved in the fossil. Taxocrinus Itliacensls differs from your 

 specimens in having- less bifurcations and in |]OSsessing almost straight 

 and not -^troiiLilv wavintr ^uturc--.'' 



HoilOCTtlNUS CRASSUS. (X. Sp. ) 



Plate 12, fig. 2. 



C'alj-x, or rather "dorsal cup," somewhat bell-shaped, rather broad 

 and slighth- inflated near the base and concavely as well a^ verj- 

 shallowly constricted a little below the middle. Height of the 

 doi-sal cup, from the lower margin of the underbasals to the sum- 

 mit of the first radials, very little greater than its maximum 

 breadth. Underbasals pentagonal, about one half the size of the 

 basals, and broader than high : basals moderately large, about equal 

 in size to the anterior radials, the three anterior ones hexagonal, 

 the two postei-ior ones hejjtagonal and truncated abuve : inferior anal 

 plate equal in size t(j the underbasals, square and resting obliquely 

 between two basals, the right i-adial and the superior anal jjlate. 

 Primary radials pentagonal, nearly flat below, slightly raised in the 

 middle above, and truncated abruptly and somewhat obliquelv, in such 

 a manner as to form a shallowly excavated articulating area whose 

 contour is almost circular, but a little broader than high, and which is 

 furnished with a small, ovate, marginal foramen, whose acutely pointed 

 apex opens directly into an obtusely angular notch in the centre of the 

 upper margin of the plate. Eight posterior radial a little smaller than 

 the rest. Sujierior anal plate pentagonal, equal in size to the right 

 po.sterior radial, but devoid of coarse of a distinct lateral articulating 

 area. .Substance of the plates thick: outer surface apparently smooth. 



Xear Thedford, Eev. Hector Currie, 1882 ; a single specimen of the 

 dorsal cup, entirely free from the matrix. 



This species may be easily distinguished from the H. scoparius of 

 Hall, from the Lower Helderberg of the State of Xew York, and from 

 the H. proboscidians of Hall, from the Oriskany Sandstone of the same 

 State, by its much larger size, by its broader, shorter and more bell- 

 shaped dorsal cup, and by the much greater thickness of the plates of 

 which this part of the calyx is composed. 



