APPENDIX E. PALAEONTOLOGY. 185 



ambulacra flexuous, extending to the base, increasing gradually in width 

 to the inferior margin ; antero-lateral are as widely divergent ; postero- 

 laterals separated by a moderate interval, mouth transverse, oval ; anus 

 oval, longitudinal sub-anal fasciole indistinct ; surface of test sparingly 

 studded with spinigerous tubercles, with numerous microscopic granules 

 in the interspaces. It approaches Holaster (Ananchytes) fimbriatus, 

 Morton, (Silliman's Journal, XVIII, 245, pi. 3, fig. 9.) Our speci- 

 mens, however, differ from the figures given by Dr. Morton in being less 

 orbicular in the oral sinus, which is not so profound, and in the anal 

 border, which is more widely truncated 



Occurs with Herniaster elegans at Fort Washita. 



Holectypus planatus, Eoemer. 



Holectypus planatus, F. Roemer, Texas, 393. Ibid, Kreidebild, 

 Texas, 84, taf. x, fig. 2, a — g. 



In the collection from Cross-Timbers, Texas, we find several mutilated 

 specimens of Holectypus, which we refer without doubt to the above 

 species. Dr. Roemer's examples were obtained from the vicinity of 

 Fredericksburg, Texas. 



