NEW AGELACRINITES 



195 



Young stages. In the earliest growth observed the rays are 

 direct and pass to the margins without curvature, ending there 

 so abruptly as to convey the impression that they extend over 

 the margin to the lower surface. In the young example figured 

 the rays are still direct, but show a gently undulating course to 

 the margin. The aboral surface of none of these young forms 

 has been seen. Many examples of this species and all the young 

 specimens are casts of the exterior. Some of the young examples 

 present rays which are but very slightly elevated along the cover 

 plates and have deeply impressed and broad marginal furrows. 



Dimensions. Adult specimens have a diameter of from 35 to 

 50 mm, and the smallest observed is 13 mm in diameter. 



Geologic horizon and localities. In the Chemung sandstones at 

 and near Alfred, Belvidere and Wellsville N. Y., and 2 miles 

 south of Sabinsville, Tioga co. Pa. 



Agelacrinites beecheri sp. nov. 

 Fig. 4-6 



Body of medium size, sessile, but not permanently attached; 

 highly convex on the oral surface with steep marginal slopes. 

 Aboral surface flat or concave. 



Thecal plates squamous, imbricating and conspicuous over the 

 interradii. Marginal plates just outside of the arms irregularly 

 elongate but not much larger 

 than those of the interradii. 

 Outside of this is a wall of nu- 

 merous small and acute peri- 

 pheral plates. 



Rays 5, departing from a 

 deeply quinquepartite and 

 hence small and narrow, oral 



depression: flagellate, 4 contra- ^''°™ ^^ mtemal cast of the oral surface, shows 



' the direction of the rays but is defaced about 



solar, 1 solar, the latter adja- *^® ^^^^ aperture, fig. S is a fragment showing 



R 3, 4, 5 and the narrow oral aperture. Fig. 6 

 cent to the anal pyramid with *s an enlarged sketch of the subambulacral 



plates drawn from a squeeze of tig. 4. 



which it is approximate. 



Radial cover plates triangular and interlocking along the 

 median line. At the base the ambulacra have a pavement con- 



v; 



Figs. 4-6 A. beecheri, natural size. Fig. 4 is 



