Weno and Pawpaw Formations 



pearance is due to the smallness and flatness of the numerous ptales: #hi(5h 

 make up its area. Infero-marginal plates as described for the supero- 

 marginals, and paired with them; however, there are only six inflated 

 terminal plates separated to the tip of the ray by the ambulacral groove: 

 The common terminal closing plate is restricted to the aboral side. Infero- 

 marginal plates finely granulose. 



Interambulacral areas of oral side broadly triangular with numerous 

 crescentic, coarsely granulated small plates in roughly concentric rows. 

 An adambulacral row of plates with combs of spines lies next to the 

 ambulacral grooves. Between these and the marginals is one row of 

 plates over most of the length of the ray, but on approaching the inter- 

 radial areas other rows enter. Peristome central, apparently protected 

 by fine incurved spines. 



The species resembles in form Nymphaster radiatus Spencer (Lower 

 Chalk, Upper Cenomanian), from which it differs in the shape and orna- 

 mentation of its marginal plates. It also has resemblances to Pentaceros 

 boysii Forbes and P. squamatus Forbes, both from the Upper Chalk of 

 Kent, England (Senonian), but it differs in these in its form and in the 

 ornamentation of the plates. 



ECHINOIDEA 



LEIOCIDARIS SP. 



Cidarids are known from all the Texas Washita formations above the 

 Fort Worth limestone. These are undescribed and their tests and spines 

 unrelated with one exception, Leiocidaris hemigranosus Shumard from 

 the Denton formation, of which spines and test have been found in such 

 close proximity that they almost certainly belong to the same animal. 

 Cidarid plates, apparently of a Leiocidaris, are abundant in the Quarry 

 limestone group of the Red River region and with them occur great num- 

 bers of spines. In addition, in the Pawpaw clay and in the Grayson marls 

 there are several different species of large cidarid spines. In the Main- 

 street limestone well preserved cidarid tests are known. 



Cidarid sp. 1, spine: The commonest echinoid spine of the Quarry group has the 

 following characteristics : 



The shaft bears about sixteen carinae which are made up of rows of rounded, bead- 

 like tubercles, whose tips are slightly pointed down the shaft. The rows are even 

 topped and depressed. On some spines certain carinae are elevated considerably above 

 others and are longer, more prominent, and have a sharp serrate keel and a triangular 

 cross-section. The spine is a short oval in cross-section. Below the tip of the shaft 

 several, in part alternate, carinae end, and the remaining ones become more elevated 



