Weno and Pawpaw Formations 133 



teriorly and then makes an acute re-entrant angle (25 degrees) passing 

 now anteriorly and almost perpendicularly to its former course; it runs 

 in almost a straight line to the anterior one-third of the valve, where it 

 gently curves upward meeting the postero-ventral corner of the scar of 

 the anterior adductor muscle. 



This scar is roughly pear-shaped and its tip is continuous postero-dor- 

 sally with an elevated ridge which passes along the bottom of the pit for 

 the resilium. Dorsal to it, the elevated margin of the valve runs poster- 

 iorly, stopping short at the middle of this pit. This pit is subcircular and 

 lies anterior to the central tooth just dorsal to its mid-dorsal point is the 

 umbo. Posterior to it is a circular elevation which is separated by a con- 

 stricted neck from the post-adductor muscle scar. 



LOCALITY : Cut in Frisco railroad, three-fourths mile north of Union 

 Station, Denison, Texas, in Weno marl, 20 feet below Quarry limestone 

 (locality 604). 



CORBULA LITTORAL1S n. sp. 

 PI. 10, fig. 5 



MEASUREMENTS: (Type) length of valve 18.0mm. 



Length of rostrum 4.0 mm. 



Height of valve _ 11.5 mm(?) 



HORIZON: "Buff marl," near middle of the Weno formation, and 

 immediately below zone of abundance of Gervilliopsis invaginata (White) 

 in association with Venericardia wenoensis, Trochus laticonicits, cidarid 

 spines, Trigonia clavigera and Placosmilia sp. 



LOCALITY : 601, pit of brickyard, one and three-fourths miles south- 

 east of Gainesville, Texas (type locality). 



A fragmentary right valve, lacking umbo, antero-dorsal margin and 

 posterior half of ventral margin is apparently different from any other de- 

 scribed species, and it is considered best to describe it here. The indi- 

 vidual is rather similar to C. wenoensis Adkins. 



Right .valve, exterior: The (restored) contour is elongate-triangular, 

 with probably a nearly straight antero-dorsal margin, a sharply rounded 

 anterior angle (probably about 60 degrees), a long nearly straight ven- 

 tral side, curving up only slightly to meet the ventral margin of the ros- 

 trum. The rostrum is short, truncate, and the form of an isosceles tri- 

 angle ; its rounded postero-ventral angle is 100 degrees ; its sharp postero- 

 dorsal angle is 110 degrees; an almost obsolete shallow oblique groove 

 separates it from the body of the valve, forming the base of the isosceles 

 triangle. The postero-dorsal side is nearly straight except for a slight 



