lis Hill — Pahoiiloloiiii of the Trlnilii Dk'iMon. 



Eiiphyla pikensis Hill. 

 Plate IV, Figs. 4, 5, 6. 



(hrhlcala pikcn,sis Hill. Arkansas Geological Survey, Annual 

 Report 18SG, vol. ii, p. 131, plate ii, figs. 13, 13a, 14, 15, 16, 17. 



This form was originally figured by the writer under the ge- 

 neric name of Corhlada, and is very closely allied to the so-called 

 Cijrena astarteforinis Koch and Dunker, from the Wealden of 

 Germany. Professor INIarcou has referred it to the Adartidn'., 

 but it is undoubtedly a S})ecies of the genus Erij)hyla of the 

 Astartida! distinguished by the lateral teeth. 



It occurs in great al)undance in Pike county, Arkansas, and 

 sj)aringly at the i)lant bed of the Paluxy, near Glen Pose, Texas. 



Requienia texana (?) (Iloeiiier). 



Caprotina texana Roemer. Kreidebildungen von Texas, p. 80, 

 plate Vj figs. 2<i, 21). 



A Requienia, provisionally referred to R. texana Roemer, is one 

 of the prominent species of the Glen Rose beds and occurs in 

 massive agglomerate some twenty feet in thickness at Glen Rose, 

 Thorp Springs, Granbury, and in southern Parker county. In 

 Roemer's description he asserts that it is indistinguishable from 

 Requienia lonsdalU D'Orb., of the French Neocomian, except by 

 its thicker shell. It is desirable to closely compare this form 

 with R. patarjiata AMiite.''^ Dr. Roemer says that the latter s})e- 

 cies is entirely distinct, the larger valve of R. texana not being 

 so elevated as in R. patagiata. Ill the abundant material col- 

 lected by the writer this distinction does not always hold good, 

 yet there is a general difference in appearance, especially in the 

 larger size and more rounded character of the valves of the Glen 

 Rose forms, which may make it a distinct species from either of 

 these. The type forms of the R. texana Roemer and the R. 

 patagiata White occur in the horizon which we at present accept 

 as the Caprina limestone, while the Requienias of the agglomerate 

 at CJranljur}^ and at the base of the Colorado section occur 

 several hundred I'eet belcjw them, and may prove a distinct 

 species. 



Requienia is the lowest occurring genus of the aljerrant Chain- 



* Requienia paUtgiata White. U. S. Geological Survey, Bulletin No. 4, 

 p. 0, plate v, llgs. 1-8. 



