﻿388 DESCRIPTIONS OF NEW SPECIES OF 



smaller in the middle than elsewhere, doubling in thickness and changing their 

 direction on the umbonal ridge, and continuing somewhat larger posterior to the ridge 

 than in advance of it ; .there is a furrow immediately posterior to the ridge, about 

 equal in size to the ridge itself. 



Dimensions. — Length - 45 in., width 1*3 in., height of valve *1 in. 



Locality. — Caldwell Co., Texas. My collection. 



NCETIA, Gray. 



N. pulchra. PL 67, fig. 55. Subquadrangular; beaks small, incurved; umbonal 

 slope nearly straight ; anterior margin rounded, basal arcuate, posterior subangular ; 

 surface marked by numerous radiating and transverse lines ; edge crenate within ; 

 posterior muscular scar subtriangular, anterior subrhomboidal. 



Dimensions. — Length *27 in., width *35 in. 



CRASSATELLA, Lam. 



H C. antesteiata. PL 67, fig. 53. Subquadrate; beaks very small ; umbonal slope 

 wide, umbonal ridge rounded ; anterior margin semicircular, basal regularly arcuate, 

 posterior subbiangular ; surface marked by numerous, large, transverse folds, which 

 commence at. the anterior margin, but disappear before reaching the middle of the 

 shell, leaving the rest almost perfectly smooth, (this is not the result of attrition) ; 

 interior margin very delicately crenate, anterior muscular impression semilunar, 

 posterior subquadrate. 



Dimensions. — Length *5 in., width "6 in. 



ANOMIA, Linn. 



"-"' A. ephippioides. PL 67, fig. 59. Very irregularly subquadrate, sometimes nearly 

 circular, sometimes almost triangular ; convex, occasionally marked by longitudinal 

 rugae, and always by distinct lines of growth ; lower valve, the muscular foramen 

 large ; ligament margin thickened. 



Size of largest specimen. — Length 1°5 in., width 1*3 in. 



Common. 



SERPULA, Linn. 



S. Texana. PL 67, fig. 41. Triangular, surmounted by a longitudinal ridge, 

 transversely rugose ; aperture subquadrangular. On shells. 

 Dimensions. — Diameter *01 in. to '02 inch. 



FLABELLUM. 



F. pachyphtllum, Gabb and Horn. PL 69, figs. 1, 2, 3. Flat, wedge-shaped, 

 edges forming an acute angle; edge coarsely toothed; sides longitudinally striate, 



