A New Ammonite Fauna of the Lower Turanian of Mexico 189 



small individuals figured by Choffat 1 in figures 3 and 4 of plate 7 and 

 figure 2 of plate 10. Considering the size and state of preservation this 

 specimen is not of great stratigraphic value. 



Vascoceras (?) sp. is a pretty large specimen which is very similar to 

 Ammonites arnesensis Choffat. The generic determination is not quite 

 certain as is also the case with A. arnesensis. Our specimen is a little 

 twisted ; it does not have much importance for the determination of the 

 age of the beds. 



Vascoceras mohovanense n. sp. is a specimen relatively small but very 

 characteristic; it belongs certainly to the group of Vascoceras polymor- 

 phum Pervinquiere of the lower Turonian of Tunis. It differs from the 

 type by a missing intermediate row of nodules but in its general character 

 and also in its suture is nearly related to the type. Pervinquiere considers 

 Vascoceras subconciliatum Choffat from the Turonian of Portugal as a 

 form of the same group but this species is different from ours on account 

 of its general form and its suture. 



The species described by me as Neoptychites aff. cephalotus Courtiller is 

 a juvenile specimen which resembles greatly the small individuals of the 

 cited species, as has been demonstrated in the paleontological part of this 

 paper. The group of Neoptychites cephalottts characterizes the lower Tu- 

 ronian ; it occurs frequently in Algiers and Tunis, also in the neighborhood 

 of Saumur, France. Similar and perhaps identical forms have been found 

 in India (Neoptychites Telinga Stoliczka) 2 and in Kamerun (Neoptychites 

 Telingaeformis Solger 3 ) ; the aee of the beds where these latter species 

 have been found is not exactly known. 



The form which I compare with Neoptychites xetriformis Pervinouiere, 

 is not very well preserved but resembles sufficiently the species from Tunis. 

 Pervinquiere considers as a nearly related form Neoptychites crassus Sol- 

 ger, 4 the age of this latter species is not determined with certainty. 



In the limestones of Horizon III we find frequently cephalopods which 

 resemble very much the bicarinated Hoplitoides of Pervinauiere. The 

 greater part of these specimens is entirely corroded but in one I have been 

 able to prepare a portion of the interior whorl which clearly shows the ex- 

 istence of the two lateral keels on the ventral portion ; one also notes the 

 suture in part, certainly much destroyed but showing the same elements as 

 in the bicarinated Hoplitoides. A large specimen has the external form of 



'Choffat, Especes nouv. cm peu conn. 



2 Stoliczka, Ceph. Cret. Rocks India, p. 125, pi. 62; Kossmat, Sudind. Kreideform., 

 p. 71, pi. 7, fig. 1, pi. 17, fig. 13. 

 'Solger, Mungokreide, p. 108. 

 'Solger, Mungokreide, p. 119, pi. 3, fig. 5. 



