114 University of Texas Bulletin 



and this position of the apical system is to some extent correlated with 

 the elongation of the test. The anterior ambital notch in E. wenoensis 

 is always sharper and deeper than in E. bravoensis; in the latter species 

 it has the same form as in H. riovistae here described, while in this respect 

 E. wenoensis and H. longisulcus (Adkins and Winton) are closely similar 

 to each other. In E. wenoensis there is a conspicuous high point on the 

 median .carina halfway between the apical system and the posterior end 

 of the test; in E. bravoensis and H. riovistae the carina is low and the 

 highest point is variable, often lying near the apical system. E. bravoensis 

 in addition has a distinctly angular inferior inflation to the test which 

 in our species is evenly rounded. 



ENALLASTER BRAVOENSIS Bose 

 PI. 8, fig. 4 



1910: Enallaster bravoensis Bose, Inst. Geol. Mex., Bol. 25, p. 168, pi. 41, figs. 5-10; 



pi. 42, figs. 2-12; pi. 43, figs. 1-2, 6-7. 



1916: Enallaster bravoensis Whitney, Bull. Amer. Pal. No. 26, p. 16, pi. 6, figs. 3-5. 

 1920: Enallaster bravoensis Adkins and Winton, Univ. Texas Bull. 1945, p 58 pi 9 



fig. 11. 



This species is occasional in the Upper Washita formations, Weno to 

 Buda, and in North Ttexas is still unknown from the lower formations. 

 At Cerro de Muleros it is reported from subdivisions 5, 6, and 8 (Fort 

 Worth to Grayson). This species differs from Enallaster wenoensis, which 

 also is truncated and tapering posteriorly, by its more elevated and in- 

 flated form, smaller depth of ambulacral grooves, and its taller and dif- 

 ferently shaped longitudinal section in which the anterior slope is shorter, 

 more abrupt and more rounded. 



ENALLASTER sp. aff. TEXANUS (Roemer) 



There are in the Upper Washita formations undefined species similar 

 in form to Enallaster texanus (Roemer). These are abundant in the 

 Weno and Grayson marls, and are in need of study and revision. 



HEMIASTER CALVINI Clark 



PI. 5, figs. 1, 2, 4; PL 6, fig. 3; PI. 8, fig. 6 



This species may be recognized by its tall rounded form and its short, 

 deep ambulacral grooves. It is somewhat variable in form and size, but 



