14 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 95 



oi narrow and curved, and in the three large oral plates characteristic 

 of the genus instead of numerous small ones. It is not the young of 

 some other edrioasteroid because the numerous specimens discovered 

 all maintain the same maximum size with the typical structure of the 

 genus. 



Occurrence. — Richmond, Warren County, Ohio, and Versailles, 

 Indiana (Waynesville formation), Oxford, Ohio (Liberty), and 

 Adams County, Ohio (Whitewater). 



Cotypes. — U.S.N.M. nos. 40742, 42111, 68333. 



HEMICYSTITES (AGELACRINITES) RECTIRADIATUS (Shideler), 1918 



Plate 5, fig. 10 



The type specimen of this magnificent species is a flattened theca 

 about 18 mm in diameter attached to a clay pebble. It is characterized 

 by long, narrow, straight arms tapering only at their extremity, sepa- 

 rated by wide interambulacral areas covered by large polygonal, 

 little imbricating plates and with an oral area of one large and two 

 small plates, all encircled by a broad band of marginal plates, very 

 large in the inner row and small around the edge. Comparison with 

 the very similar H. chapmani is noted under that species. 



Occurrence. — Richmond (Lower Whitewater), Olive Branch, 

 Harshaville, Adams County, Ohio. 



Holotype.—\J.S.^.M. no. S-3954. 



HEMICYSTITES DEVONICUS, n. sp. 



Plate 7, fig. I 



Theca small, 6 mm in diameter, attached to a Chonetes. The inter- 

 ambulacral and oral plates are rather large and somewhat disturbed, 

 but show distinctly that the rays are exceptionally short, straight, 

 broad at the oral end, and taper very rapidly, with only 4 or 5 plates 

 to a row. Other features as in the genus. The very short, rapidly 

 tapering ambulacral rows distinguish this species from all others of 

 the genus. 



Occurrence. — Devonian (Long Lake beds), abandoned shale pit of 

 Alpena Portland Cement Company, Alpena County, Michigan. 



Holotypc. — Collection Geological Department, University of Michi- 

 gan, no. 17295. 



