Weno and Pawpaw Formations 125 



the valve. The growth lines on the valve are fine but unequal; there are 

 also irregular coarser, more widely spaced imbricated rings. 



In addition, the right valve and its ears are ornamented with numerous 

 fine striaeiform radial curved elevated costellae which spread fan-wise 

 as they approach the margin; these are irregularly truncated near the 

 ventral margin, and on the ears, by intersection with the coarser radial 

 striae, form a network of small squares. 



The left valve is apparently slightly concave and has a similar structure 

 to the right valve. 



PECTEN GEORGETOWNENSIS (Kniker) 



1919: Neithea georgetownensis Kniker, Comanchean and Cretaceous Penctinidae of 



Texas. Univ. Texas Bull. 1817, p. 31, pi. VI, figs. 1-3. 

 1920: Pecten georgetownensis Winton and Adkins, Geology of Tarrant County, Univ, 



Texas Bull. 1931, pp. 22, 64, 66. 

 1920 : Pecten georgetownensis Adkins and Winton, Univ. Texas Bull. 1945, p. 70, pi. 12, 



figs. 5-6. 



This species may be distinguished by its form and by the radial grooves 

 located on the center of the primary and secondary ribs of the right or 

 both valves. These grooves, however, occur sporadically on other species 

 of Pecten of the P. subalpinus type. It marks the basal third of the Weno 

 formation, marl facies, and is associated with Turritella worthensis, 

 Ancycloceras bendirei, Remondia acuminata Cragin, Pedinopsis symmetrica 

 Cragin, and numerous widely ranging species. It is widespread and abund- 

 ant. 



VENERICARDIA WENOENSIS n. . P . 



PI. 6, fig. 2 



MEASUREMENTS (type individual) : 



Antero-posterior 23 mm. 



Dorso-ventral . 23 mm. 



Right-left 18 mm. 



HORIZON AND LOCALITY: Basal Weno formation, marl facies, 

 locality 618, near Fort Worth, Texas (type locality) ; middle Weno shales, 

 "buff marl," below the main GerviUiopsis invaginata zone, locality 601, 

 near Gainesville, Texas. 



DESCRIPTION : This Venericardia somewhat resembles V. alticostata 

 Conrad var.: of the Eocene, but has the ribs more strongly imbricated 



