1881.] NATURAL SCIENCES OF PHILADELPHIA. 349 



botli second tertian" radials are bifurcating, and give to the inner 

 side of the ra}' a simple arm, to the outer 2X2 quaternary radials, 

 of which each series supports an arm. The plates of the upper 

 order of radials, all around the bod}', and frequently the last 

 axillary plate of the posterior raj'S, are not enclosed within the 

 body or only parll}^ so, thus remaining in a somewhat imdeveloped 

 state, while they are in form and size regular radials. Compared 

 with B. originarius, the arms are more crowded, the upper 

 portions more spatulate. Arm joints transversely angular, the 

 outer sides straight or very little convex. Vault unknown. 



Geological Position, etc. — From the same layer as the preceding 

 species, and almost as common. Collection of Chas. Waclismuth. 



Eretmocrinus adultus n. sp. 



Plates apparently without ornamentation. Calyx low basin- 

 shaped, with a projecting rim along the basals. First radials a 

 little shorter than second and third together, but wider than either 

 of them ; the third wider than the second. The higher orders of 

 radials comparatively large, composed of two plates each, which 

 increase in size upward, those forming the arm bases very much 

 wider, as large or larger than the first primary raelials. Articul- 

 ating scar or facet for the attachment of the arms occupying but 

 little more than one-half to two-thirds the width of the plates, 

 somewhat projecting, thereby producing a shallow depression 

 between the arm bases, outer face truncate or concave. The con- 

 cavity is filled by three arm pieces, a central one which is angular 

 above, and a shorter piece on each side of it, the latter of the 

 height of the regular arm joints but narrower. They are followed 

 by a similar piece on each side, and two other pieces resting 

 against the sloping sides of the little axillary plate, alternating 

 with the former, and constituting the base of two arms, which 

 from the second or third joint become free. The species has 

 fourteen pairs of arms, two in the anterior ray, and three in each 

 of the others. Arms long gradually flattening at midway, upper 

 portions strongly spatulate and folded inward. 



Interradials consisting of one large plate, succeeded either by 

 one or two smaller ones, or by a single large, elongate piece, 

 wedged in between the plates of the higher order of radials. 

 Anals one, three, and three plates. Vault unknown ; anal tube 

 long, extending considerably beyond the arms, of rather large size, 

 composed of smooth plates. E. adultus agrees in its double arm 



