202 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Se«. 



great value in giving paleontologists an excellent connec- 

 tion with the Miocene of America, since of all forms in the 

 Tertiary the stages of the horse are best known. 



Finally, a Tertiary fauna from Magdalena Bay, Lower Cali- 

 fornia, was recently discovered and submitted to Dr. B. L. 

 Clark of the University of California for identification. This 

 fauna as determined by Dr. Clark and the writer contains the 

 following species : Rceta gibbosa Gabb, Pecten oxygonum 

 optimum Brown & Pilsbry, Pecten condylomatus Dall, Pec- 

 ten gatunensis Toula. Pecten oxygonum optimum occurs at 

 Gatun, and near Tuxpan, Mexico. Pecten condylomatus is 

 reported from near Tampa, Chattahoochee formation, Florida, 

 and Tuxpan, Mexico. Pecten gatunensis is also found at 

 Gatun and Tuxpan. The type specimen of Turritella tristis 

 came from Costa Rica. Turritella tristis Brown & Pilsbry 

 and several other forms not specifically but generically deter- 

 mined which are characteristic genera of the Bowden stage 

 were also recognized. Recta gibbosa Gabb was described from 

 the Tertiary of Peru and it also occurs in strata equivalent to 

 the Bowden in United States of Colombia. All of these local- 

 ities are Bowden equivalents or associates as judged by their 

 associated faunas. 



The evidence concerning the lower Oligocene or Vicksburg 

 stage is quite deficient and it is impossible to determine any 

 connections at this time. 



Beds of Eocene age containing several species common 

 to the Tejon of California occur along the Mexican Gulf 

 border. White limestones in the Isthmus of Tehuantepec may 

 be of Eocene age. The faunal relationships between the Mexi- 

 can coastal plain and the Tejon of California indicate that 

 there were straits which were probably situated in the Isthmus 

 of Tehuantepec during upper Eocene time. The lack of close 

 faunal relationships during the Martinez-Eocene stage with 

 those of the Midway indicates the opposite conclusion. Ac- 

 cording to Stanton^* the Pacific and Texan Cretaceous have no 

 species in common. Although Stanton recognizes the presence 

 of an upper Cretaceous series containing a Pacific fauna rest- 

 ing upon a lower Cretaceous, Comanchian stage at Catorce, he 



"Stanton, T. W., Jour. Geol., vol. 3, 861, 1895. 



