ACTINOCEINID^. 599 



plates beautifully granulated. Interambulacral plates flat. Orals crowned 

 with a small central tubercle, as are also the plates roofing the ambulacra, 

 which are irregularly arranged, and decrease in size as they approach the 

 arms. 



Horizon and Locality. — Lower Burlington limestone; Lake Valley, New 

 Mexico. 



Tt/pe in the collection of Prof. Cope. 



Physetocrinus lobatus W. and Sp. (nov. spec). 

 Plate LXIII. Figs. 8a, b. 



Calyx proportionally higher than in the preceding species, height to 

 width as ten to nine ; distinctly lobed at the arm regions. Dorsal cup some- 

 what bulging, slightly constricted across the distichals. Ventral disk almost 

 flat ; interradial and interdistichal spaces — the latter from near the summit 

 of the disk to the second row of interbrachials — deeply grooved, giving to 

 the surface of the tegmen, and to the upper part of the cup a sharply lobed 

 outline. Ornamentation of the plates similar to that of P. Copei ; but the 

 ridges, as a rule, more prominent, the inner faces of the triangles deeper, 

 and all enclosing; a second triang-le within the outer one. 



Basals moderately short, forming a cup with slightly projecting lower 

 margin, and small notches at the sutures; axial canal small and pentangular. 

 Eadials and costals as long as wide, or a little longer; the first costal two 

 thirds the size of the radials and hexangular, the second somewhat larger 

 than the first, and heptangular. Distichals and palmars small, both even 

 with the costals, but raised considerably above the interradial spaces. The 

 distichals give off an arm to the outer sides of the rays, the palmars two 

 arms, making six to the ray. Structure of the arms unknown. Eegular 

 interbrachials : 1, 2, 2, 2 ; the anal plate followed by 2, 3, 3, 2 plates ; the 

 upper row at all sides in contact with the plates of the tegmen. Plates of 

 the disk almost flat, small, and of uniform size ; their arrangement irregular, 

 except on approaching the arms, where they become alternate. Orals inde- 

 terminable, and probably wanting. Anal regions slightly bulging, the open- 

 ing directed anteriorly. 



Horizon and Locality. — Lower Burlington limestone ; Lake Valley, 

 New Mexico. 



Types in the collection of Wachsmuth and Springer. 



