210 SYSTEMATIC PALEONTOLOGY 



Family HETEROCRINIDAE 



Genus HETEROGRINUS Hall 



HETEEOCKINUS HETEEODACTYLUS Hall 



Plate LIII, Figs. 6, 7 



Heterocrinus heterodactylus Hall, 1847, Pal. New York, vol. i, p. 279, 



pi. Ixxvi, figs. la-o. 

 Heterocrinus heterodactylus Meek, 1873, Geol. Surv. Ohio, Pal., vol. i, p. 12, 



pi. i, figs. la-b. 



Description. " Body short, rounded, subcylindrical, tapering above 

 and below; pelvis composed of five small pentagonal plates, which are 

 succeeded by the same number of larger costal plates, and these again by 

 five scapulars ; arms irregularly subdivided ; column pentagonal, composed 

 of thick joints, which are nodulose at the angles; joints alternating in size 

 as they approach the pelvis. 



" This is a peculiar species, remarkable for the small size of the body 

 when compared with the column. The irregularity of the arrangement 

 of the plates in the arms and fingers is likewise a striking characteristic 

 of the species, which is constant in two specimens from different localities. 

 In one of the arms, the scapular plate supports a regular series of six or 

 more plates of similar form without division. The arms at the right and 

 left of this one are again unlike each other. The one on the left has 

 three regular and gradually diminishing joints above the scapular, and 

 of the same form; the last one supports the cuneiform joint, which again 

 supports a double row of joints (or a pair of fingers). The arm on the 

 right of the first mentioned consists of a pair of quadrangular joints, 

 each of which supports a cuneiform joint. In the remaining two arms, 

 no plates have been traced beyond the scapulars, and consequently the 

 entire form of the species cannot be determined. Sufficient is visible, 

 however, to show the irregular character of the arms, from which its name 

 is given." Hall, 1847. 



Occurrence. MARTINSBURG SHALE (Eden division). Pennsylvania 

 and Maryland. A splendid mold of a well-preserved, entire calyx with a 

 considerable column attached was found at Jordans Knob, one and one- 



