132 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



continuous body of Neo-Cretaceous deposits have certainly 

 been traced into this Aquismon Bay, and, so far as our pres- 

 ent information goes, have not been certainly recognized in 

 the valley south of the scarp which forms its southern boundary, 

 except in remnantal areas. 



They have been observed in a narrow outcrop stretching 

 southeastward from Tamazunchale and in scattered areas as 

 far south as Tecualontepec on the upper part of the Rio Espi- 

 nal-Tecolutla. To the south of this they seem to have been 

 entirely eroded. 



Since the Papagallos of Aquismon Bay is identical with 

 that farther north and shows no indication of approach to 

 shore conditions, nor any reason to look for its immediate 

 discontinuance, the sudden change in character of the mate- 

 rials southward, the Tertiary fossils of the Tanlajas beds and 

 the finding of Eocene fossils at Alazan and of fossils of sup- 

 posedly Eocene age in the underlying beds at Sabanita, gives 

 support to the idea that a large portion, if not all, of the 

 shales south of Aquismon belong to the Eocene, and are, 

 therefore, of later age than the Papagallos and that the 

 Papagallos, if it formerly extended over this area, as it most 

 probably did, was eroded or is now covered by the beds we 

 have called Chicontepec. 



The Alazan shales are definitely proved by their fossils to 

 be of Eocene age and are also known from similar fossils 

 found in a well at Topila on the Panuco River. They are 

 apparently unconformable on the underlying blue shales. 

 Just how far these Alazan shales extend northward and what 

 portion of the beds on the Panuco River belongs to the Papa- 

 gallos and what to the Alazan or other Tertiary horizon, is 

 unknown. 



Prof. Cummins found what seemed to be the Papagallos 

 type of shales exposed at a few localities north of the Tux- 

 pam River, but, until better information and criteria for iden- 

 tification are at hand, it will be safer to treat the unfossilifer- 

 ous beds of shales, clays, and sandstones, with occasional 

 beds of limestone, which, in the region south of Panuco 

 River, occur between the Tamasopa or San Juan and the 

 Oligocene, as undifferentiated Chicontepec, which is referred 

 to the Eocene. 



