33 St. Maurice and Claiborne Pelecypoda 23 



collection from near Negreet P. O., La. shows this feature in a 

 remarkable degree . The broad ribbed variety we have named 

 cainei.SQ.^ below. Also see fig. 8, t3'^pe of variety. From the 

 sellcefonnis , light-colored layers near the base of the bluff at Clai- 

 borne thin, varietal forms are found, one of which herewith fig- 

 ured (fig. 5) is quite as large as the average deshayesi from the 

 sends above. It is characterized by the scaly spinosity of the bi- 

 partite ribbing shown on valves of willcoxi Dall (fig. 6), and de- 

 scribed also as deshaysei var. tirnuis by de Gregorio. 



The intimate relationship of some forms oi deshayesi Sind waii- 

 tubbeanus may also be noted by the fact that the usual small right 

 valves generally known as lyelli, in the collection of the U. S. 

 Nat. Mus. , No. 116,012, are classed as wazitubbeanus . 



Type. — U. S. Nat. Museum. 



Horizon. — St. Maurice Eocene. 



Specimens figured. — Wautubbee and Hickory, Miss. var. ; 

 fig. 5 from base of bluff at Claiborne. 



Localities. — Simpkins place, 3 mis S. E. of Negreet, and St. 

 Maurice, La ; Wautubbee, Hickory, 8 mis W. of Enterprise, 

 Miss. ; 3 mis S. W. of Orangeburg, S. C. ; Coffeeville, base of 

 bluff at Claiborne, Ala. 



Pecten (wautubbeanus var?) willcoxi Dall, PI. 14- Figs. 6, 7. 



P. ( IVautubbeaniis) var. willcoxi Dall, Trans. Wag. &c., vol. 3, 1898, 

 p. 737, pi. 29, fig. 4. 



Dalls original descinpiton— Shell small, broad, flattish, thin ; left 

 valve with about sixteen narrow, rounded, elevated ribs, with somewhat 

 sparse, regularly spaced prickles on their tops ; between the ribs are similar, 

 but lower and smaller, non-dichotomous radial threads ; submargin very 

 narrow, nearly plain, with faint Camptonectes striation ; ears small, subequal, 

 ejtcept the byssal ear, which is longer, narrow, with a deep sinus and con- 

 spicuous fasciole, and about sixty scabrous radii, the right posterior ear with 

 concentric striae and only faint traces of a few radii ; the ears on the left 

 valve similar, with five or six strong scabrous threads ; internal basal margin 

 of left valve with short flutings in harmony with the radial sculpture ; the 

 disk not grooved ; in the right valve the internal channels are more pro- 

 nounced ; the right hinge line has a single crural ridge parallel with the 

 margin on each side of the pit. Alt. 23, lat. 24 mm. 



This form is closely related to P. wautubbeanus, from which it differs 

 by the isolated character of the prickles on the ribs, which are replaced in 

 wautubbeanus by more or less continuous concentric lamellation, while the 



