89 St. Maurice and CIvAiborne Pelecypoda 89 



Lirodiscus ssnithvillensis 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 original 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 striae ; 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 of the typical foi-m.—D&viVs Eye, Colorado River, Bastrop 

 Co. ; Smithville, 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 figures of the smaller Burleson Co. 

 specimens given in the Proceedings of the Phila. Academy. 



The specimens photographed are in the Cornell Paleont- 

 ological Museum. 



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 S7ibge?ieric characterization. — Shell of moderate size, 

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

 of the exterior, but undulating peripherally, especially basally ; 

 lunule and escutcheon linear. 



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

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



DalPs original description of psychopterus. SheW 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-diajneter 1.3 mm. 



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



