Contributions to Palceontology. 29 



angular form, peculiarly prolonged basal pieces, and the absence of the 

 usual sculptured ornamentation of the plates. 



The specimen figured was found b}- E. Eeinhardt, and is now, as 

 well as those from which the description was drawn, in the collection 

 of C. B. Dyer. 



Pal^aster SIMPLEX,* u. sp. (Plate I., fig. fi.) 



[Ety. — Simplex, simple, plain.] 



Pentagonal; rays longer than the diameter of the body, and uni- 

 formly tapering. The marginal plates rapidly diminish in size, from 

 the body, toward the points of the rays, and change from a somewhat 

 oblong shape to a nearly globular form as the}' approach the tips of 

 the rays. The marginal plate, at the junction of the rays, is remark- 

 ably large and somewhat angular-ovate in form; the smaller end extends 

 up between the adjoining marginal plates, which it supports on the 

 upper sloping sides, while the larger end extends into the angle formed 

 by the junction of the adambulacral plates. Only nine marginal plates, 

 in addition to the one at the junction of the ra^-s, are preserved on a 

 single side of an}^ ray in the specimen collected, but as the raj's to 

 this point have gradually contracted to less than half the width at the 

 bod}^, it is presumed that they extended but little farther. 



There are twent3^-two somewhat oblong adambulacral plates, ar- 

 ranged with their length across the raj^s, and their breadth in the 

 direction of the length of the rays, between the oral plates and the 

 end of the ninth marginal plate. 



There are ten oral plates formed by the junction of the adambulac- 

 ral rows, each one of which has an irregular, somewhat elliptical form, 

 with a triangular extension into the oral opening. 



No ambulacral plates are visible, and the ambulacral groove is so 

 exceedingly narrow, that it could not have contained more than a 

 single row of ambulacral ossicles. 



The dorsal surface, madreporiform tubercle, and outer limits of the 

 rays unknown, and likewise the ambulacral ossicles, though some 

 small pieces of crinoidal matter in one of the raj's ma}^ represent some 

 of them. 



The description is founded upon the ventral side of a single speci- 

 men, collected by W. J, Stevens, of Lebanon, in the upper part of the 

 Cincinnati Group, near Eaysville, Ohio, and now belonging to S. A. 

 Miller's collection. The diameter of the bod}^ is about two fifths of 

 an inch; length of a ray from the bod}^ to the ninth marginal plate, 

 about half an inch; thus indicating the greatest distance from the tip 



••■■ The description of this species was read by S. A. Miller, before the Society, at 

 the January meeting, 1877. 



