The Calceocrinido}. 401 



inner angle of the triangular piece, and passing through the 

 excavation for the reception of the column, to the outer margin 

 of the ^Munate-shaped'' jDiece, dividing it into equal halves. 

 This suture-line is much less distinct than the other, and is 

 consequently less noticeable. The anterior triangular piece is 

 undoubtedly formed by the union of two anterior radials. 



Having determined the composition of the consolidated basal 

 piece of the typical form of Calceocrinus, we can place here all 

 such as have the same structure. 



This will be done with all that have been found upon exami- 

 nation to correspond to the typical form as shown in a quite 

 perfect individual, so nearly like the type in basal structure and 

 surface markings, that it was at first regarded as a young speci- 

 men of that species, but further study shows it to be a closely 

 allied species differing distinctly in some minor details. 



A specific description of the original species will be found 

 under Calceocy^imis halli. 



CALCEOCRIIVUS Hall. 

 (Revised by Ringueberg.) 



Calyx and arms hanging downward and directed outward at an angle 

 from the column. 



Column round, bent somewhat posteriorly at its upper portion so as 

 to admit of a greater inclination of the calyx. 



Arms three. Anterior arm simple (?) or bifurcating near its terminal 

 portion. Lateral arms consisting of a series of axillary plates attached 

 to, and forming a more or less complete arch over the anals on the pos- 

 terior side, each of which gives rise to an armlet from its free or distal 

 end. 



Consolidated basal piece convex, semicircular, or partially triangular 

 in outline, and formed of three consolidated plates, — two lateral basal* 

 and one broadly triangular anterior anchylosed basal, which extends 

 to, or nearly to, the outer angles of the piece. 



Column attached to the suture-line dividing the lateral basals, and 

 never coming in contact with the anchylosed anterior basal. 



Calyx flattened anteriorly, rounded posteriorly. 



Anterior radial triangular, supporting on its two upper sides the ad- 

 joining lateral radials. Lateral radials meeting in the median line above 

 the apex of the anterior radial, and supporting in a broadly V-shaped 

 notch between and above them the anterior brachial. Laterally, 

 through anchylosis with the posterior radials, they extend around 

 to and upon the posterior side and assist, with the low and broad 



ANKALS N. Y. ACAD. OF SCI., IV. Issucd November, 1889. 



