1881.] NATURAL SCIENCES OF PniLADELPHIA. 337 



The name Uperocrinui^^ in a subgeneric sense, was proposed by 

 Meek and Worthen for species witli a narrow calyx, drawn out so 

 as to form a kind of handle for the upper portions, but was given 

 up afterwards. 



Generic Diagnosis. — General form of body biturbinate, wheel- 

 shaped, or globose ; calyx and vault of a similar form, the former 

 composed of smooth, slightl}^ convex to strongly nodose plates, 

 scarcely ever striated ; the dome consisting of convex or tuber- 

 culous pieces, with a strong, almost central anal tube. Symmetry 

 of calyx bilateral. 



Basals three, equal, not \ery high, forming an extended rim 

 with a concavity for the reception of the column. Primary radials 

 3X5; the first hexagonal or heptagonal, larger than the second 

 and third combined ; the second quadrangular, linear, always 

 narrower than the first, but 3'et twice or three times wider than 

 high, sometimes altogether anchylosed with the third ; the third 

 pentangular, short, the lower lateral sides abruptly spreading and 

 giving a greater width to the median portions, the upper sides 

 supporting the higher radials. Secondary radials 2 X 10, very 

 wide, as large as the primary ones ; those of the second series 

 bifurcating. The anterior ray has sometimes but two or three 

 arms, this is frequently accidental, but in some species the rule. 

 Tertiary radials 2 X 2 X 10, narrower than the secondary, 

 supporting the arms. 



In some species the posterior rays support additional plates in 

 the body, but only in the division next to the. anal area, this side 

 sometimes having one, two or three additional arms, while the 

 opposite division retains the usual number of four. The upper 

 row of plates is at the outer face truncated for the reception of 

 the arms, their upper sides being notched along the median 

 portions for the arm passages. This notch is joined by a similar 

 notch in the corresponding plates of the dome, which, combined 

 with the other, forms an arm opening (PI. 19 , fig. 2, and PI. 18, 

 fig. 8) ; the opening is oval in form, longer than wide, resting 

 within the centre of a small concavity. The part which extends 

 into the vault, follows the lateral edges of a tertiary radial dome 

 plate. The opposite side of the radial is likewise excavated to 

 receive a respiratory (?) pore, which is enclosed on the other side 

 by an adjoining interradial or interbrachial piece. Hence the 

 two openings are separated by the tertiarv radial dome plates, . 



23 



