12 Bulletin 26 96 



number of plates, about 1 2 . 



Pores variable and in undulating rows which double abo\^e 

 the ambitus near the apical system. 



Interambulacral areas, double the width of the ambulacral 

 at the ambitus; tubercles mammillated, crenulate, imperforate, 

 and arranged in two rows on each half of the area. The areolas 

 are bordered by granules forming polygons with extra large 

 granules at the corners of the plates along the median and adra- 

 dial lines. 



Peristome and apical system unknown. 



This is possibly the same as the species described by Cragin, 

 but the specimen from the Buda Limestone is fragmentary and 

 therefore unsatisfactory as a basis for determination and descrip- 

 tion. 



Number of specimens: 1. 



Occurrence: Upper division of the Buda Limestone, Austin, 

 Texas. 



PYGASTERIADM 



Genus Holectypus, Desor 



Holectypus planatus? Roemer 



Plate VII, figures 1-5 



Holectypus planatus Roemer, 1849, Texas, p. 393. 



Holectypus planatus Roemer, 1852, Die Kreidebildungen von Texas, 



p. 84. Taf. X, fig. 2. 

 Holectypus planatus Shumard, 1852, Exploration Red River of Louisiana 



Rept. p. 211. 

 Holectypus planatus, Giebel, 1853, Naturwiss. Ver. in Halle Jahresb. 



P- 373- 

 Holectypus planatus Conrad, 1857, U. S. and Mex. Boundary Surv 



Report, Vol. I, pt. 2, p. 145, PI. I, fig. 4. 

 Holectypus planatus Desor, 1858, Synopsis des echinides fossiles, p. 174 

 \ Holectypus planatus Gabb, 1859, Cat. Invert. Fossils Cretaceous, p. 18 

 Holectypus planatus Meek, 1864, Smithsonian Misc. Coll., Vol. 7 (177) 



p. 2. 

 Holectypus planatus Clark, 1891, Johns Hopkins Univ. Circ, Vol. 10 



No. 87, p. 76. 

 Holectypus planatus Clark, 1893, Johns Hopkins Univ. Circ, Vol. 12 



No. 103, p. 51. 

 Holectypus planatus Clark, 1893, U. S. Geol. Survey Bull. 97, pp. 51, 59 



PI. XXII, figs. 2a-i. 



