190 University of Texas Bulletin 



Hoplitoides mirabilis but is a little less involute. This group is of some in- 

 terest in so far as having been found only in the lower and upper Turon- 

 ian. The types of Hoplitoides mirabilis 1 and H. Munieri 2 occur in Tunis 

 mainly in the lower Turonian, H. Munieri also in the upper Turonian. A 

 similar species has been found also in the Turonian of Egypt. 3 



In the same Horizon III, Dr. E. Haarmann also collected four specimens 

 of Inoceramus of which three are typical individuals of Inoceramus labia- 

 tus Schlotheim. According to an observation made by Jose G. Aguilera, 

 this fossil occurs in great numbers in beds north of the station of Carillo 

 which apparently overlie limestones identical with those described here. 



In Horizon III occurs very frequently Avicula Aguilerae n. sp. This 

 species is very similar to Avicula- gravida Coquand which occurs in north- 

 ern Africa in the Turonian as well as in the lower Senonian or Emscherian. 

 The form and size of this Avicula are so similar to those of ours that this 

 find in Mexico has a certain stratigraphic interest. 



In the material of Horizon III we find a great number of other bivalves, 

 but all in the state of internal molds ; a specific determination is entirely 

 impossible. The most frequent form probably belongs to Tylostoma or 

 some subgenus of Natica; the greater part of the material is badly pre- 

 served, but some specimens are a little more complete, although preserved 

 as internal molds, and resemble strongly Tylostoma ovatum Sharpe which 

 in Portugal occurs in beds from the Cenomanian to the upper Turonian. 



From the character of the fauna of Horizon III we have to conclude that 

 these beds still belong to the lower Turonian. This appears rather proba- 

 ble from the circumstance that Horizon II is extremely thin and is well 

 confirmed especially by the cephalopod fauna. Interesting is the occur- 

 rence of Inoceramus labiatus Scholtheim. This fossil is extremely common 

 in Mexico and generally is found in great numbers in calcareous shales 

 and shaly limestones. The question now is, what relation exists between 

 those beds and those of Cerro del Macho? In the described locality the 

 shales, etc., do not exist, but according to the identification of J. G. Aguil- 

 era these are found north of the station of Carillo where they apparently 

 overlie limestones similar to those of the Cerro del Macho. If we accept 

 this explanation, our beds at Cerro del Macho have to be considered as the 

 lowest part of the Turonian, while the shales with Inoceramus labiatus 

 would be a little younger and perhaps represent the lower as well as the 

 upper Turonian. We have no data with which to solve this problem, as up 

 to now the beds with Inoceramus labiatus have not been found in contact 



1 Pervinquiere, Paleontologie Tunisienne, p. 218, pi. 10, fig. 3. 

 2 Idem, ibid., p. 217, pi. 10, figs. 1, 2. 

 3 Eck, Turon in Aegypten, p. 380, 386. 



