89 St. Maurice and Claiborne Pelecypoda 89 



Lirodiscus smitlivillensis Harris, PI- 31- Figs. 17-23. 



Astarte smithvillensis Har., Proc. Phila. Acad. Nat. Sci., 1895, p. 

 48, pi. I, figs. 8, a ; 9, a, b, c. 



Harris's oHginal description . — Size and general form as indicated by 

 the figures ; surface in typical specimens marked by strong concentric rugae 

 especially toward the base ; these slope gently above but abruptly below, 

 and are superimposed by fine strise ; umbones flattened. 



This species shows great variations in form and size as well as mark- 

 ings. At Collier's ferry some specimens are more elongated, others more 

 rotund ; some have crenulations on the interior submargin while others are 

 smooth. Several of these forms are shown by the figures cited. 



Locality 0/ the typical fonn.—'DftxWs^yi:, Colorado River, Bastrop 

 Co. ; Smith ville, Bastrop Co., Tex. 



Locality of the smaller forms.— 15 miles southeast of Nacodoches, Na- 

 codoches Co., Tex. 



Geological horizon. — Lower Claiborne Eocene. 



Type. — Texas State Museum. 



We give herewith photographs of Smithville specimens to- 

 gether with copies of the figtires of the smaller Burleson Co. 

 specimens given in the Proceedings of the Phila. Academ3\ 



The specimens photographed are in the Cornell Paleont- 

 ological Miisetim. 



Lirodiscus (Crustuloides) psychopterus Dall, PI. 32. Fig. i, a, b. 



Crassatellites {Scambula)psychopterus Dall, Trans. Wag., Ill, 1903, p. 

 1470, pi. 42, figs. 8, 9. 



Nezv subgeiieric characterization. — Shell of moderate size, 

 elliptical, wafer-like in flatness ; smooth on the greater portion 

 of the exterior, bnt undulating peripherally, especially basally ; 

 hinule and escutcheon linear. 



Type.—{Oi right valve, Paleont, Mus., C. U.), (of left 

 valve, U. S. Nat. Mus.). From Wautubbee, Miss. 



Ball's original description of psychopterus.S\\&\\ thin, flat, ovate, 

 rounded in front and behind, the anterior end shorter ; surface smooth ex- 

 cept for incremental lines and three or four low, distant concentric ridges ; 

 nepionic shell with little or no sculpture ; lunule and escutcheon linear or 

 obsolete ; left valve with two well-marked cardinals, the posterior dorsal 

 margin with a shallow groove for the edge of the opposite valve ; basal 

 margin with a row (in the adult) of minute pustuliform crenations. Long. 

 20.0, alt. 15.0, semi-diameter 1.3 mm. 



The single valve upon which ( with a fragment of a larger specimen ) 



