454 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 59. 



The specific description, based on a single incomplete and some- 

 what weathered lower valve, is as follows: 



SAUVAGESIA DEGOLYERI, new species. 



Plates 96 and 97. 



Lower valve large, elongate-conical, apparently slightly curved; 

 shell thick, cellular, the cell walls forming a coarse reticulation in 

 cross section, such as is characteristic of the genera Sauvagesia and 

 Durania; cross section probably nearly circular when perfectly pre- 

 served but subelliptical in the type which shows evidence of some 

 compression; internal ligamental ridge well developed, indicating 

 reference to Sauvagesia rather than Durania; surface ornamented by 

 about 20 to 25 moderately strong longitudinal costae which are 

 apparently broader than the interspaces; siphonal bands not dis- 

 tinctly recognized on account of the weathered condition of the 

 specimen. 



Height of imperfect lower valve, 190 mm.; greater diameter at top, 

 95 mm.; smaller diameter at top, 70 mm. 



Weathering has almost removed the costae so that their exact 

 number and form are not determinable, but the bottoms of the 

 grooves between the principal costae remain, and the weathering 

 gives longitudinal sections of the costae showing the cells in each 

 costa arranged in curved lines with the irregular concavity upward. 



This species has a superficial resemblance to Barrettia monilifera 

 Woodward, but the shell structure is totally different from that 

 characteristic of the genus Barrettia. In size, form, general appear- 

 ance, and minute shell structure Sauvagesia degolyeri is very much 

 like an undescribed species of Sauvagesia in the United States Geo- 

 logical Survey collection from the upper part of the Brownstown marl 

 near White Cliff, Arkansas. This suggests that the San Felipe forma- 

 tion may be on approximately the same horizon as the Brownstown 

 marl; that is, within the zone of Exogyra ponderosa, but the evidence 

 is not sufficient to justify making the positive correlation. It is 

 certain, however, that the lower part of the San Felipe formation in 

 which this Sauvagesia was collected is of Upper Cretaceous age. 



Type.— Cat. No. 32482, U. S. N. M. 



EXPLANATION OF PLATES. 



Plate 96. 



Sauvagesia degolyeri Stanton. Side view of type, slightly less than natural size. 



Cat. No. 32482, U.S.N.M. 



Plate 97. 



Sauvagesia degolyeri Stanton. Cross section of type, slightly less than natura size. 



Cat. No. 32482, U.S.N.M. 



