Fauna of the Buda Limestone. ' 15 



convex, geniculate, ornamented with eight strong, radiating 

 costas, terminating in hollow, lamellar spines, at the genicula- 

 tion. Below the geniculation, the surface is marked by heavy 

 lines of growth, with only a trace of the costae. Right valve 

 ornamented with five or more radiating costas extending to the 

 margin and bearing four concentric rows of spines. 



The hinge and interior were unknown when, in my thesis, I 

 described this shell as Plicatula genicidata n. sp. Recently, 

 however, material has been gathered, indicating that it should 

 be referred to the genus Anomia. 



Locality. Shoal Creek, Austin, Texas. 



MYTILIDAE. 



Genus MODIOLA Lamarck. 



MODIOLA AUSTINENSIS n. Sp. 



PL II, fig. 6. 



Dimensions. Length, about 40mm. ; breadth, 18mm. 



Description. Shell elongate, subcuneate, arcuate, inflated an- 

 teriorly, compressed posteriorly; beaks subterminal, twisted for- 

 ward ; umbonal ridge prominent, sloping abruptly to the ante- 

 rior ; surface ornamented with concentric lines of growth, crossed 

 by numerous fine striae radiating from the beak, and covering 

 the entire shell. 



Locality. Shoal Creek, Austin, Texas. 



PHOLODOMYACIDAE. 



Genus HOMOMYA Agassiz. 



HOMOMYA BUDAENSIS n. sp. 



PL III, figs. 1, 2. PL IV, figs. 1, 2. 



Dimensions. Length about 110 mm. ; breadth, 60mm. ; thick- 

 ness 61mm. 



Description. Shell large, globose, equivalved, inequilateral, 

 greatly produced and broadened posteriorly; anterior margin 

 short, curved; ventral margin deeply curved; posterior margin 

 broadly rounded; dorsal margin curved, subparallel with ven- 

 tral; umbos globose, approximate, elevated, curved inward and 



