4 PEOCBBDINGS OF THB NATIONAL MUSEUM. vol.61. 



So far as my present knowledge of the subject goes, the San Felipe 

 limestone appears to correspond approximately in age to the San 

 Juan limestone of Dumble.^ The Mendez shale undoubtedly corre- 

 sponds to at least a part of the Papagallos shale of Dumble, but there 

 appear to me to be good reasons for believing that the Papagallos 

 includes beds that are stratigraphically higher than the typical Men- 

 dez as it is developed in the southeastern part of the State of Ta- 

 maulipas. 



Future critical study of the foraminifera which abound in both 

 the San Felipe and Mendez formations will in my opinion result in 

 the discrimination of faunal zones that will make possible a close 

 correlation of these formations with beds of corresponding age in 

 northern Mexico and in Texas. Inasmuch as the Mendez shale and 

 the Taylor marl were laid down under similar conditions of deposi- 

 tion, a comparison of the foraminiferal faunas of these two forma- 

 tions ought to be particularly fruitful of results. 



The crinoids from the upper part of the San Felipe formation and 

 from the lower and upper parts of the Mendez shale are described 

 and their significance discussed by Dr. Frank Springer in Article 5 

 of this volume of the Proceedings. The crinoid stems are all referred 

 to the genus Balanocrinus in the family Pentacrinidae, and are 

 described under the new specific name B. mexicanus. 



DESCRIPTIONS OF NEW FORMS. 

 TAMPSIA, new genus. 



The two forms described below under the specific names Tampsia 

 hishopi and T. chocoyensis present generic characters which appar- 

 ently have not been heretofore described. The lower valve is large, 

 elongate, conical, and thick shelled. In both species the close crowd- 

 ing of the individuals in the colonies has caused irregularities of 

 growth and coarse scars and imperfections of greater or less size. 

 The shell structure of the outer shell layer, which alone is preserved, 

 is very fine as compared with that of the genera Sauvagesia and 

 Durania, and the polished cross section exhibits numerous fine, con- 

 tinuous, concentric growth lines. These growth lines inclose rows of 

 small cells which vary greatly in size and shape due to the irregulari- 

 ties of growth; many of the cells are squarish or rectangular, but 

 some of them are irregular in shape and are five or six sided. (See 

 pi. 3, fig. 2, and pi. 4.) 



There is no internal ligamental ridge, nor is there any trace in the 

 cell structure of a feature corresponding to this ridge. The inner 



1 Durable, E. T., Geology of the northern end of the Tampico embayment area : Pioc. 

 Cal. Acad. Sciences, vol. 8, No. 4, pp. 125-133,, 1918. 



