Vol. VIII] DUMBLE-GEOLOGY TAMPICO EMBAYMENT AREA 151 



Cypraea, sp. 



Ficus, sp. 



Malea ringens Swainson 



" sp. 

 Melongena. sp. 

 Natica, sp. 

 Olivella, sp. 

 Sinum, sp. 

 Ttirritella, sp. 

 Urosalpinx, sp. 

 Xenophora, sp. 



Bose states that the Semijoval division which overlies the 

 Eocene deposits in Chiapas may possibly include both Oligo- 

 cene and Miocene deposits. This division consists of argil- 

 laceous shales, blue clays, gray sandstones, and limestones. 

 The fauna, which was not carefully studied, embraced ostrea, 

 sp. ; pecten, sp. ; turritella, sp. ; stromhus, sp. ; conus planiceps, 

 echinolampas, sp. ; clypeaster cf. meridianus, etc. in the shales, 

 with some corals and pectens in the limestones. From this it 

 would appear that there is seemingly a strong resemblance be- 

 tween the Semijoval and the San Rafael, just as there is be- 

 tween his Chiapas Eocene and the Chicontepec. 



NEOCENE 



North of the Tuxpam River sedimentary beds of later age 

 than the Oligocene seem to be confined to those of late Pliocene 

 or Pleistocene age. 



In the northern portion of the Embayment area, lynig be- 

 tween the Tamaulipas Range and the Cordilleras we find, rest- 

 ing directly on the Papagallos shales, beds of materials cor- 

 responding in every way to the Reynosa of Southwest Texas 

 and Northeastern Mexico. It consists of conglomerates, 

 gravels, and sands, with some clays and more or less calcareous 

 cementing material, which, in many places, takes the form of 



Ccilicric 



Similar beds are found east of the Tamaulipas Range and 

 southward throughout the area. 



East of the Tamaulipas Range we find overlying the Oligo- 

 cene clays and sands, in a number of localities, a rather heavy 



