FOSSIL ECHINI OF THE PANAMA CANAL ZONE AND 



COSTA RICA. 



By Robert Tracy Jackson, 



Of Peterborough, New Uampshire. 



INTRODUCTION. 



The fossil echini of the Panama Canal Zone were submitted to me 

 for study and description by Dr. T. Wayland Vaughan as part of the 

 studies he is making in that region in connection with his investiga- 

 tions of the geology of the Coastal Plain of the United States and of 

 the West Indies. Tiie material contains some very interesting 

 species, particularly in the genus Encope, of which there are three 

 new forms. Some of the material is well preserved, and parts are 

 fragmentary. A number of specimens too poorly preserved, or too 

 fragmentary for specific determination, indicate that a more ex- 

 tensive echinoid fauna may be found by further search. 



I wish to express my heartiest thanks to my friend. Dr. Hubert 

 Lyman Clark, of the Museum of Comparative Zoology who, with his 

 great knowledge of Clypeastroids and Spatangoids, helped me 

 materially in preparing this report. 



LIST OF SPECIES AND THEIR GEOLOGIC OCCURRENCE. 



Olypeaster lanceolatus Cotteau. Oligoceno, Emperador limestone 



Gaillard Cut, stations 5S666, 6671. 

 Olypeaster gatuni, new species. Upper Oligocene^ Gatun formation, 



station 5662, near Gatun Dam site; and at station 6237, north 



of Ancon Hill, about 4 miles south of Diablo ridge. 

 Encope annectans, new species. Upper Oligocene,* Gatun formation, 



station 5846, Spillway, Gatun Dam. 

 Encope platytata, new species. Upper Oligocene,' Gatun formation, 



station 6029a, one-quarter to one-half mile from Camp Cotton, 



toward Monte Lirio. 

 Encope megatrema, new species. Upper Oligocene,* Gatun formation, 



station 6030, about one and one-half miles from Camp Cotton, 



toward Monte Lirio. 

 EcTiinolampas semiorhis Guppy. Oligocene, Emperador limestone, 



Gaillard Cut, stations 58666 and 6019G. 



' This formation perlnps may moro appropriately be referable to the lower Miocene, I. e., Burdigallan. 

 For a recent discussion of the geologic age of the mombers of the Apalachicola group in Florida and 

 Georgia, see Vaughan, T. W., The reef-coral fauna of Carrizo c eek, IrafJerial County, California, and it» 

 Blgnificance: U. S. Gcol. Survey, Prof. Pap. 9»-T., pp. 3S3-366, 1017— T. W. V. 



Proceedings U. S. National Museum, Vol. 53— No. 2218. 



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