GEOLOGY AND PALEONTOLOGY OF THE CANAL ZONE. 207 



CyathormorpJia antiguensis (Duncan), Antigua, etc. 

 Goniopora species. Similar to Antiguan species. 

 Although the identifiable species are few, it appears safe to cor- 

 relate the San Rafael formation with the Antigua formation. 



TONOSI, PANAMA. 



Doctor MacDonald obtained at this locality, station 6587, the fol- 

 lowing species of corals: 



Astrocoenia guantanamensis Vaughan, Antigua, Cuba. 



Favia macdonaldi Vaughan, Antigua. 



Maeandra antiguensis Vaughan, Antigua. 



Trochoseris meinzeri Vaughan, Cuba. 



Diploastrea crassolamellata (Duncan), Antigua, Cuba, etc. 



There can be no reasonable doubt that this is the same as the coral 

 fauna found in the Antigua formation. As the locality at which 

 the specimens were obtained is on the Pacific coast of Panama, the 

 evidence is conclusive that there was middle Oligocene connection 

 between the Atlantic and the Pacific in that area. 



SERRO COLORADO, ARUBE. 



Three species were obtained at this locality, 1 as follows: 

 Orbicella insignis (Duncan), Antigua. 

 Antiguastrea cellulosa (Duncan), Antigua. 



Gonio'pora species (the kind of casts to which Duncan applied the 

 name Alvepora daedalea var. regularis). 



This fauna is evidently the same as that of the Antigua formation. 



CONCLUDING REMARKS ON THE MIDDLE OLIGOCENE. 



The foregoing lists show that Antiguan middle Oligocene coral 

 fauna is known in Porto Rico, Cuba, southern Georgia, southern 

 Alabama, eastern Mexico, Panama, and Arube. That it also occurs 

 in Santo Domingo is known from some of the specimens, Siderastrea 

 conferta (Duncan) typical and a peculiar variety of Asterosmilia 

 exarata (Duncan), both brought from Santo Domingo by Gabb. It 

 is a key horizon in the American Oligocene. The Byram calcareous 

 marl of Mississippi occurs either at its base or just below its base. 

 It therefore overlies all the Vicksburgian lower Oligocene, with the 

 possible exception of the uppermost member, and is stratigraphi- 

 cally just below the "silex bed" of the Tampa formation. The 

 correlation of the deposits containing this fauna with the Rupelian 

 of Veneto has been made on page 202. 



That there was middle Oligocene connection between the Atlantic 

 and the Pacific was pointed out on this page in discussing the species 

 from Tonosi, Panama. 



1 Vaughan, T. W., Some fossil corals from the elevated reefs of Curacao, Arube, and Bonaire, Geolog. 

 Reichs-Mus. Leiden Samml., ser. 2, vol. pp. 1-91, 1901 (especially pp. 11, 12). 



