AHT. 1. KUDISTID SHELLS FROM MEXICO STEPHENSON. 9 



station, near the northeast corner of fraction 101, about 64 kilome- 

 ters northwest of Tampico, State of Tamaulipas, Mexico. Collected 

 by A. W. Beckley and the writer. 



Type.—C2Li. No. 32500, U. S. N. M. 



Geologic 'position. — Upper part of Mendez shale, an Upper Cre- 

 taceous formation corresponding in age approximately to the Taylor 

 marl of Texas. 



SAUVAGESIA DEGOLYERI Stanton (?). 



Plates &-10. 



Sauvagesia degolyeri Stanton, Proc. U. S. Nat. Mus., vol. 59, No. 2379, 

 pp. 453-454, pis. 96-97, 1921. 



Description. — Fragments of Radiolitidae which closely resemble 

 Sauvagesia degolyeri Stanton, recently described from the San 

 Felipe formation near Puente Diablo between Valles and El Abra, 

 in the eastern part of the State of San Luis Potosi, Mexico, were 

 found by the writer in the upper part of the San Felipe formation 

 at three localities on Las Flores hacienda and at one locality on 

 Chocoy hacienda. These fragments exhibit numerous moderately 

 rounded to rather sharp crested, irregularly developed longitudinal 

 ribs separated by deep V-shaped channels, and the cell structure is 

 very similar to that of S. degolyeri. The portion of the surface 

 shown in plate 9, figure 1, is back of the posterior siphonal area. 



On one incomplete young specimen, which was flattened by lateral 

 compression before the internal cavity had an opportunity to become 

 filled with matrix, the surface sculpture is preserved practically all 

 the way around the shell (pi. 10) ; the anterior siphonal band E is 

 somewhat distorted by the compression to which the shell was sub- 

 jected, but it is flat, about 12 mm. wide, and marked by 6 or 7 small 

 longitudinal ribs separated by deep, sharp channels a little narrower 

 than the ribs; the posterior siphonal band (S) is also flat, 12 to 20 

 mm. wide, broadening upward, and is ornamented by 7 to 12 small 

 ribs which increase in number from below upward by bifurcation; 

 two ribs, a larger and a smaller, separated by deep V-shaped cavi- 

 ties occupy the area between the two siphonal bands. 



The ligamental ridge (L) which characterizes the genus is clearly 

 though imperfectly preserved on several of the fragments. 



Owing to the poorly preserved condition of the ribs on Stanton's 

 type specimen it is impossible to refer these fragments to his species 

 with confidence. De Golyer states in the quotation given by Stanton 

 that he found the type specimen in a bed 80 to 100 feet (25 to 30 

 meters) above the base of the San Felipe formation. I have recently 

 visited the locality, and in my opinion the containing stratum is not 

 in the lower part of the formation, but is above the middle, and is 



