82 PALEONTOLOGY OF NEW-YORK. 



Fig. 1 tt. A nearly perfect individual of this species, with portions of the fingers and several inches of 

 the column attached. The column, in its different parts, shows the structure which the other 

 fragments of columns present. 



The body is composed of plates arranged as follows : 

 Fig. 1 b. E. Pelvis, composed of five small pentagonal plates. 



~. First costal plates five, hcptagonal, resting upon the upper and inner edges of the pelvic 

 plates. 



-. Second costal plates five, hexagonal, resting upon the upper edges of the costal plates. 

 b 



H. Scapulars five, hexagonal, and resting directly upon the last. 



G. Intercostal plate. 



1. Double interscapular plates. 



The intercostal plate supports upon its upper lateral edges a pair of interscapular 

 plates, which are in turn succeeded by two other pairs of similar plates; the last pair 

 truncated on their upper angles, and more deeply excavated between, supporting on the 

 upper and inner lateral edges a small quadrangular plate, and upon the truncated upper 

 edges a pair of larger quadrangular plates. 

 K. Brachial plates. Each of the scapulars is surmounted by a hexagonal brachial or arm- 

 plate, which supports a double cuneiform arm-joint \, from which proceed the hands 

 and fingers m, n. 

 Fig. 1 c. Part of one of the tentaculated fingers of this species. The tentacula are long, and not jointed ; 

 the joints of the fingers are cuneiform, the tentacula being attached to the broader side of 

 each joint. 

 Fig. 1 d. A part of one of the fingers magnified, showing the tentacula attached to ths broader side of 



the plate. 

 Fig. 1 e. A fragment of a small column. / The same enlarged, showing characters precisely similar 



to the fragments of larger columns. 

 Fig. 1 ^. A column of large size; the upper part showing the larger thick plates, which are nodulose 

 on their margins, aUernating with three thinner plates : lower down the number of inter- 

 mediate plates becomes four, and below this five, when the central one becomes thicker and 

 broader, the edges projecting beyond the others. 

 Fig. 1 A. A fragment of a small column ; the surface worn nearly smooth, and presenting only the 



points of attachment of the side-arms on the thicker joints. 

 Fig. 1 i. A small column ; the larger joints unusually projecting, and their edges elevated. 

 Fig. 1 h, I, m. Fragments of columns from diflx'rent parts, showing the alternation of larger and smaller 

 plates, points of attachment for side-arms, and the weathered surface exhibiting the serrated 

 appearance of the edges of the plates. 

 Fig. 1 n, o. Specimens showing the character and aspect of fragments of different parts of the column. 

 In some portions there are six, seven, and eight intermediate plates, the central ones usually 

 extending a little beyond the others, and showing a nodulose margin. 

 Fig. 1 f. Ends of the plates of the columns, showing a striated surface. 



This column, though so variable, is still so different from the columns of other species, 

 that there will be no difficulty in recognizing the species even from small fragments. 



