Manual of the Paleontology of the Cincinnati Group. 



129 



ginal ones, forty-two or forty-three in number, the basal ones (oral) ten, 

 in pairs, small, elongated, subtriangular ; upper surface of rays with 

 numerous small, tuberculose or sub-spinose plates; madreporiform 

 tubercle large, situated laterally at the base of two rays. (Rept. N. 

 Y. State Mus. Nat. Hist., 1866, p. 285 : 20th Rept. N. Y. State Mus. 

 1870, p. 327.) 



Locality. — Cincinnati, O. 



5. — P. exculptus S. A. Miller, 1881. 



Pentagonal; diameter of body about 0.9 of an inch; rays a little 

 longer; breadth of ray at body about three -fifths of an inch, obtusely 

 pointed : marginal plates somewhat quadrangular, the first eight occu- 

 pying about one-half inch; eighteen in one inch, and about twenty- 

 five on each side of each ray ; surface tuberculated and probably 

 spinous; adambuiacral plates about twenty-eight, narrower than, but 

 about the same length as the marginal ones, spinous ; a single some- 

 what pentagonal "plate between the junction of marginal plates and 

 of each ray ; ambulacral furrow wide ; each plate with a sharp ridge, 

 increasing in height as it approaches the adambuiacral row of plates. 

 (Jour. Cin. Soc. Nat. Hist., vol. 6, p. 69.) 



Locality. — Waynesville, O. 



6. — P. miamiensis S. A. Miller, 1885. 



Pentagonal; rays 0.9 inch long; diameter of body 0.6 inch; 

 rays obtuse ; marginal plates wider than long, about twelve in one- 

 half inch from body, with two at junction of rays; ambulacral groove 

 wide : ambulacral plates eighteen in one-half inch, each with an 

 angular ridge; adambuiacral plates about same size as marginal ones, 

 and alternating with them, as shown by the figure, no mention being 

 made in the description. (Jour. Cin. Soc. Nat. Hist., vol. 3, p. 143.) 



Locality. — Waynesville, O. 



7. — P. spinulosus Miller and Dyer, 1878. 



Body pentagonal; rays longer than diameter of body; marginal 

 plates globular near ends of rays, but lengthened toward the bases, 

 six measuring three lines ; junction of marginal plates with body 

 formed by two wedge-shaped plates ; ambulacral groove deep and 

 wide; ambulacral plates with their greatest length across the rays, 



