PELECYPODA—TELEODESMACEA. 539 



Differs from V. conradi in its thicker and larger shell, and pres- 

 ence of the projecting growth lamellae only upon the younger 

 portion of the shell ; the rest being covered only by strong wrinkle- 

 like ridges. 



Ripleyan of New Jersey (Navesink, Tinton), Gulf region. 



495. V. mortoni Meek and Hayden. Cretacic. 

 Differs from V. trigona in being more oblique, more depressed 



at the beaks, which are also placed directly over the more trun- 

 cated anterior margin. Dorsal margin also longer, giving it a 

 greater proportional length, and less sloping. 

 Benton : Colorado, Montana. 



496. V. humilis Meek and Hayden. (Fig. 737.) Cretacic. 



Fig. 737. Veniella humilis, anterior and left views. (After Meek, Surv. Terr., IX.) 



Umbonal slope rounded. Surface concentrically striated. 

 Fox Hills : South Dakota, Wyoming, Colorado. 



CXXXVII. Astarte Sowerby. 



Shell thick, inequilateral, usually rounded triangular or oval, 

 closed, with smooth or concentrically sculptured exterior. Epi- 

 dermis thick. Lunule impressed; escutcheon elongate. Ligament 

 external. Two cardinal teeth present in each valve ; the right an- 

 terior strong. Lateral teeth rudimentary. Adductor scars strong, 

 nearly equal ; above the anterior is a pedal impression. Pallial 

 line simple. Jurassic-Recent. 

 497. A. carlottensis Whiteaves. Comanchic. 



Subcircular to transversely subovate in outline, moderately and 

 regularly convex. Length and height about equal. Margin form- 

 ing a continuous subelliptical curve from the posterior end of the 

 hinge to the lower end of the lunule. Hinge short and gently 

 convex. Beaks about half way between the middle and anterior 



