54 [Assembly 



ACTINOCRINUS YIMINALIS ( n. s.). 



Body short and spreading, broadly cyathiform and deeply lobed 

 at the rays. Basal plates very small : first radial plates pro- 

 portionally large ; second radial plates broad, quadrangular ; 

 third radials very short and broad, pentangular, and supporting 

 brachial plates on their upper sloping sides. 



Arms two from each ray at their origin, composed of a double 

 series of plates beyond the third or fourth above the third 

 radial. The arms are sometimes almost regularly bifurcating 

 near the base, and unequally divided above this. In one anterior 

 ray the arm is regularly bifurcated below; one division again 

 subdividing into three, and the other into five arms or branches. 



The interradial areas consist of one small plate below, with two 

 elongate plates above, which are situated between the bases of 

 the arms. The first anal plate is smaller than the first radial 

 plate, and above this they have not been determined. 



The dome is large, ventricose, somewhat lobed in the direction 

 of the rays, composed of numerous small flat polygonal plates. 



Plates of the body little convex, sometimes elevated along the 

 middle or approaching to subangular, with the surface striato- 

 granulose. 



Column of medium proportions, composed of thin alternating 

 joints. 



In the mode of bifurcation of its arms, this species resembles the A. whiti of the 

 Burlington limestone; but the form of the body is very different. In this one, the 

 arms become free above the third radial plates; while in that one they are united to 

 the cup by interbrachial plates, and lise from the body in ten divisions, while these 

 are free before subdividing, and present but five arms where they become free. 



GENUS PLATYCRINUS ( Miller). 



PLATYCBINUS CONTRITUS (n.s.). 



Body broad and short, broadly truncate at the base for the re- 

 ception of a large column. Basal plates forming not more than 

 one-third the height of the cup : radial plates wider than high. 

 Arms short and strong, composed of a double series of plates, 

 bifurcating on the second radial plate, which is subpentangular 

 with short lateral sides : divisions four from each ray, except 

 on the postero-lateral ones, where there are three on the anal 

 side, making five to each of these rays ; giving a formula of 



Surface smooth. 



JZS. = 22 arms. 



5 5 



This species is of the type of P. burling tonensis; but there is no described 

 species which approaches this one very nearly in the detail of its characters. 



