PROCEEDINGS OF THE UNITED STATES NATIONAL MUSEUM 



issued ll^ik S 0?^l ^H '^' 



SMITHSONIAN INSTITUTION 



U. S. NATIONAL MUSEUM 



Vol.84 Wathington : 1937 No. 3015 



MEXICAN FOSSIL ECHINI 



By Robert Tracy Jackson 



Museum of Comparative Zoology, Cambridge, Mass. 



The collection of fossil Echini reported upon in this paper was 

 submitted to me for study by Dr. T. Wayland Vaughan. All types 

 of new species described herein are in the United States National 

 Museum except that of Lovenia mexicana, which is in the museum of 

 the California Academy of Sciences, San Francisco. 



I should express my warm appreciation to my friend Dr. Hubert 

 Lyman Clark for his help in this work. His opinion is of great value, 

 especially in the cidaroids and clypeastroids, for the indentification in 

 these two groups is exceptionally difficult on account of the multi- 

 plicity of species, and Dr. Clark is a high authority on both groups. 

 Assistance in stating precisely the localities and the geologic horizons 

 has been kindly rendered by J. M. Muir and Thomas F. Grimsdale. 



The regular Echini are represented by only two species of Cidaris 

 and one of Stomopneustes. This last is of exceptional interest, as it 

 is the first recorded occurrence of the genus as found fossil in America. 

 Indeed, its previous occurrence as a fossil anjnvhere is somewhat 

 doubtful. The clypeastroids, as usual in Tertiary collections, are 

 rather abundant in species and individuals. Of spatangoids there are 

 a number of species, and the specimens are in an exceptionally good 

 state of preservation. 



128736—37 227 



