140 Cincinnati Society of Natural History. 



range of each ray are included within the disc, the series ending 

 abruptly about one and one-half lines from the oral plates; sixteen 

 plates in each range on the rays; pores apparently closed by obtusely 

 conical or pyramidal plates, some with a depression in the top; mar- 

 ginal plates flat placed on edge and directed outward so as to overlap 

 each other, the edges toward the ventral surface and pointing toward 

 the ends of the rays, lined with ten or twelve short, club-shaped spines ; 

 dorsal surface of rays with two rows of alternating and interlocking 

 plates, deeply sculptured near the disc and about as long as wide, 

 becoming gradually less excavated and longer in proportion to the 

 width at the tips of the rays; on each side they articulate with the 

 upper edge of the oblique marginal plates; disc 0.60 inch broad ; 

 rays o. 16 inch broad at disc, and 0.88 inch long from the oval plates. 

 (Jour. Cin. Soc. Nat. Hist., vol. 5, p. 95.) 

 Locality. — Covington, Ky. 



Remarks. — In this lengthy description we have many of the 

 generic characters repeated. The author says it is " related to Pro- 

 taster flexuo sits " M.andD. 



2. — P. flexuosa (M. and D.) sp. 1878. 



Disc varying in diameter from one-quarter to one-half inch, com 

 posed of very thin, small plates; rays very flexuous, the dorsal surface 

 with four series of plates on each side near the disc, the two inner 

 forming an angular ridge, alternating, and presenting an appearance 

 like two series of hour-glasses; outer or marginal plates spinous, the 

 spines directed toward the apex of the ray ; three series of pores on 

 the rays ; plates slightly longer than wide and about four to one line ; 

 rays cross the disc on the dorsal side and unite near the centre ; ven- 

 tral surface with two rows of spines springing from the marginal plates 

 on each side of the rays. (Jour. Cin. Soc. Nat. Hist., vol. 1, p. 31 

 as Protaster.) 



Locality. — Cincinnati, O. 



Remarks. — This species seems to present an aggregate of charac- 

 ters which justifies in placing it in Protasterina. The principal one of 

 these characters is the interlocking series of plates presenting the hour- 

 glass appearance. 



(To be continued.) 



