50 Bulletin 4 164 



by lines of growth. 



'' Dimensio7is. — Length, .3 in., width, .6 in., greatest height of 

 valve, .2 in. 



''Locality. — From the marls and alternating limestone of the 

 Ripley Group, Hardeman Co., Tenn." 



Fig. 4 is from bed b at Hannah's, Hardeman Co., Tenn. Fig. 

 5 from Texas, is probably of the same species. 



Type. — Not found in the material sent by Dr. Safford. Lost? 



LITHODOMUS. 



Lithodoimis gainesensis n. sp., PI. 3, figs. 7, a. 



Specific characterization. — General form as shown by the figures; 

 cylindrical; half the size indicated; umbones anterior, very incurv- 

 ing; no teeth; shell thin, marked exteriorly generally by a few 

 concentric low undulations; one specimen shows three or four 

 radiating lines posteriorly; valves apparently entirely closed; no 

 radiating lines seen near the anterior. One specimen was col- 

 lected which is nearly twice the ordinary size. 



Locality. — Uppermost Midway Eocene limestone exposed at Ft. 

 Gaines, Ga. Very common. 



Type. — Paleontological Museum, Cornell Univ. 



ARCA. 



Area sp., PI. 3, figs. 8, 9, a. 



This little A7^ca is quite common in the uppermost layer of the 

 Midway limestone at, Ft. Gaines. It is characterized by rather 

 strong concentric folds, which become tuberculate or spinose 

 where crossed by radii; the latter comparatively few in number 

 and strong on the anterior slope; anterior half of the face of the 

 valve with fine radii; posterior coarser and becoming very coarse 

 and spinose at the umbonal angle; posterior to this, both concen- 

 tric and radiating sculpturing, well defined. Specimens of some- 

 what larger size are found near the base of the Midway on the 

 Chattahoochee not far above the mouth of Sandy creek. Another 

 large specimen presumably of this species, was found in a cotton 

 field I mile north of Midway. It has a decidedly Area mississip- 

 piensis-like aspect. It is about ^ of an inch in length. It seems 

 unwise to name this species until its relations with the , other 

 Eocene Arc<z can be more fully investigated. It has the aspect of 

 "JVavieula asperd" Con. or of Area lyelli of England. 



