237 LiGNiTic Stage 45 



slight external striation and color patches. 



In general we feel great hesitation in assigning specimens 

 from both sides of the Atlantic to the same species. But in this 

 case Dixon's figures represent the American form so precisely 

 that it would seem absurd to propose for it a new name. That 

 Aldrich's Peden alabaniensis is a precursor of this and should 

 be reckoned as a subspecies only, will probably be shown here- 

 after. The main points of difference between this and A . ala- 

 ba77iense are : ist. In sqtiamulum from Woods bluff there are 

 normally 9 ribs, exceptions are rare ; the exterior of squamulum 

 is smooth except sometimes the left valve is finely striate ra- 

 dially ; the right valve of alabamense is finel}^ sharply, stri- 

 ate concentrically and is superimposed generally by very strong, 

 sharply defined raised lines or costae which cause nodulations 

 at their intersedlion with the stronger concentric lines ; the 

 curvature of the valves of alabamense is uniform ; in squa- 

 mulum there is a slight flattening anteriorly and posteriorly just 

 below the umbonal ridge, and there are yellowish color patches 

 scattered about over the left valve. Cossmann has with pro- 

 priet}^ referred lyamarck's P. squaimda to Amtcssmm ( Extr. 

 Ann. Soc. Roy. Mai. de Belg., vol. xxxi, 1896, App. 2, p. 63), 

 It is slightly gaping fore and aft, has strong interior ribs, is 

 practically smooth exteriorly, and has internally slight projec- 

 tions on the lower portions of the ridges formed by the ears. 

 It may be observed, however, that the ears of this species are 

 rather large for Amussmm and that there is a decided slit be- 

 neath the anterior ear of the right valve for the passage of a 

 byssus. This feature together with the strong markings of A . 

 alabamense Aid. show that the limits of the genus Amussium 

 must be somewhat enlarged. 



Locality. — Alabama : Woods Bluff. 



Specimens Jigured. — Woods Bluff. Paleont. Mus., Cornell 

 University. 



Chlamys greggi, n. sp. PI. 7, figs. 4, 5. 



Syn. ? P. deshayeii Aid., Bull. No. i, Geol. Surv. Ala., p. 57, 1886. 



Specific charaH: eristics. — General appearance as figured ; ex- 

 terior with about 25 to 30 strong, smooth, sharply defined ribs 

 radiating from the beak without bifurcation, ears with 5 or 6 

 radiating folds or costae ; interspaces about twice the breadth of 



