> A New Ammonite Fauna of the Lower Turanian of Mexico 227 



rich material could decide if it would not be better to separate these two 

 groups at least subgenerically. It was probably the want of sufficient ma- 

 terial which decided Pervinquiere not to separate the two Turonian species 

 from the rest of the genus. If such study should prove that all the species 

 from the Turonian belong to .the bicarinate group, it would be better to 

 unite them in a different species. 



The main difference between our species and H. mirabUis consists prob- 

 ably in the larger diameter of the umbilicus, but our material is not suffi- 

 ciently well preserved to allow a more detailed comparison. 



The two species of bicarinate Hoplitoides described by Pervinquiere oc- 

 cur in the lower Turonian ; one of them has also been found in the upper 

 Turonian (H. Munieri). 



Eck 1 cites with some doubt Hoplitoides mirabilis, or a similar form, from 

 the Turonian of Egypt. Woods 2 describes a Hoplites Nigeriensis from Ni- 

 geria which he takes to belong to the bicarinate Hoplitoides. These spec- 

 imens occur in probably Turonian beds. In the same locality have been 

 found Vascoceras Gongilense Woods and Pseudaspidoceras sp. Woods 

 mentions that Hoplitoides has also been found in another locality of Ni- 

 geria. 



Number of specimens : 2, and 4 fragments. 



Age: Lower Turonian (Salmurian), upper horizon. 



LAMELLIBRANCHIATA 



AVICULA Bruguiere 



AVICULA AGUILERAE sp. nov. 



PI. 20, figs. 1-2, 11-12 



The material from the upper horizon of the Salmurian of Cerro del 

 Macho contains a number of specimens of a large and well characterized 

 Avicula. Its features are : 



Shell thin, of subquadrate form, nearly as high as broad, not very con- 

 vex ; the right valve is a little more convex than the left one. On the an- 

 terior side is a prolongation in form of an auricula which is not quite com- 

 pletely preserved but which certainly was not very long ; on the posterior 

 side we note a prolongation in form of a wing, with a precise limit be- 

 tween this wing and the rest of the shell. The auricula as well as the wing 



!Eck, Turon in Aegypten, p. 382 and 386. 



2 Woods, Cret. dep. Northern Nigeria, p. 284, pi. 23, fig. 3; pi. 24, figs. 1-5; fig. 1 

 of the text. 



