1897.] NEW YORK ACADEMY OF SCIENCES. 373 



•except the lateral margins of the infrabasals, ornamented by nar- 

 row papillose bands parallel to the sutures. Exclusive of these 

 papillose bands the plates are smooth. 



Infrabasals five, large, extending far beyond the column, an- 

 <3hylosed into an irregularly hexagonal, nearly flat disk, the su- 

 tures marked by slightly elevated ridges ; central portion of the 

 disk slightly excavated for the attachment of the column, the 

 excavation surrounded by a low ridge. 



Basals five, four of them broader than high, spherical-triangu- 

 lar in outline, in lateral contact only at the extreme lateral 

 angles. The posterior basal higher than wide, quadrangular in 

 outline, truncated distally for the reception of the special anal 

 plate, the lateral and proximal sides curved as in the four other 

 plates. 



Radials five, large, twice as wide as high, the three anterior 

 ones heptagonal in outline, the two posterior ones hexagonal. 

 The proximal sides concavely curved to conform to the curved 

 sides of the basals, the proximal angles meeting the distal angles 

 -of the infrabasals and the lateral angles of the basals. 



First brachials twice as wide as high, pentagonal in outline, 

 bearing upon the two upper sloping sides the two main divisions 

 of the arms. 



Arms uniserial, the component plates broader than long, ex- 

 cept near the tips, rectangular in outline except the axials, which 

 are pentagonal. In the right posterior arm, the only one known, 

 each main division bifurcates several times, the most posterior 

 one showing ten subdivisions at the tip. 



Badianal nearly as large as the basals, pentagonal, higher than 

 wide, lying upon the truncated right posterior infrabasal and be- 

 tween the posterior basal and the right posterior radial. 



Special anal larger than the radianal, hexagonal, higher than 

 wide, lying upon the truncated posterior basal and between the 

 radianal and the left posterior radial. 



First tube plate partially included in the calyx, higher than 

 wide, lying upon one of the upper sides of the radianal and be- 

 tween the special anal and the right posterior radial. 



Ventral sack very large, expanding above and surrounded at 

 its summit by a row of large, spatulate, spinose plates which 

 form a crown of diverging spines upon the summit of the sack. 



Remarks. The form of the plates in the dorsal cup of this 

 species differs materially from the other species of the genus, but 

 the A'^entral sack, which is the most remarkable feature of the 

 genus, and which is said by Wacksmuth and Springer* to be the 

 best character for distinction, is in all respects like that in the 



♦Revision of the Paloeocrinoidea, I., p. 130. 



