169 St. Maurice and Claiborne Pelecypoda 169 



Macoma sillimani Conrad, , PI. 51, Figs. 6, 7 



Tellina sillimani Con., Amer. Jour. Sci., vol. i, 1846, p. 399, pi. 4, 



fig. 9. 

 T. {Metis ?) sillimani Dall, Trans. Wag., Ill, 1900, p. 1016. 



Conrad's original description. — Subtriangular, compressed, thin ; left 

 valve with a prominent, acute fold over the umbonial slope, which is 

 straight ; posterior side shorter than the anterior ; the dorsal line straight 

 and oblique ; the end margin obliquely truncated, and the extremity trun- 

 cated ; surface marked with brown concentric bands ; valve contracted 

 widely from beak to base between the middle and the umbonial slope. 



Claiborne, Alabama. Very rare. 



We illustrate herewith a specimen that seems to be fairly 

 close to Conrad's type. But the contraction Conrad speaks of 

 between the middle and the umbonal ridge is a very variable fea- 

 ture. Most specimens are without it. This particular specimen 

 is unusually contracted. The specimens without the contrac- 

 tion seem to be very close to ehirneopsis from the Jacksonian. 

 The umbonal slope is thus characterized: (ist) on the umbonal 

 ridge (right valve) there is an obscurely raised radiating ridge, 

 (2) just behind this an obscure radiating channel, (3) from here 

 to the posterior edge of the valve the area is undifferentiated. In 

 the left valve the position of the fold and channel is reversed. 



The posterior of the whole shell is bent somewhat to the 

 right. The brown bands are broad and conspicuous. So far we 

 have observed no lateral teeth. 



Type. — Phila. Acad. 



Horizon . — Claiborne Eocene . 



Specimen figured. — Paleont. Museum Cornell Univ. 



Locality. — Claiborne, Ala. 



Macoma danai, n. sp., PI. 51, Figs. 8, 9 



Specific characterizatioji. — Shell more or less circular and ro- 

 bust as illustrated ; more capacious than sillimani, umbonal slope 

 with a radiating fold crossed diagonally by lines of growth, be- 

 hind which the post-umbonal slope area abruptly faults down, 

 but gradually rises again to the posterior margin ; dentition as 

 in sillimani ; pallial line and sinus confluent below, without the 

 sharply upraised sub-sinus just beneath the umbo shown in silli- 



