A New Ammonite Fauna of the Lower Turanian of Mexico 



portion of the last whorl is a little corroded, but there are certainly more 

 than forty on the last whorl. The suture is not visible. 



Dimensions: 



Diameter 94mm. (1) 



Height of the last whorl 36 mm. 0.40 



Width of the last whorl 60 mm. .0.64 



Diameter of the umbilicus 31 mm. 0.33 



Height of the last whorl on the same diameter but half a whorl 



backwards 27 mm. 0.29 



Width of the last whorl at the same point 55 mm. 0.59 



On account of its general form and its ornamentation I place this speci- 

 men in the genus Fagesia although the suture could not be made visible. 

 Our species is quite similar to Fagesia tevesthensis Peron 1 especially the 

 large specimen figured by Pervinquiere- (pi. 20, fig. 6). This individual 

 shows on the umbilical border nodules quite similar to those of our speci- 

 men. But the African species has much broader and lower whorls which 

 in part may be explained by its stage of development, because all the 

 species of Fagesia change their cross-section of the whorls with their age 

 and grow more rapidly in width than in height. 



Another species which resembles ours is Fagesia rudra Stoliczka. 3 This 

 species shows very similar ribs and the umbilical border is entirely smooth. 

 Fagesia rudra differs from our species by its much broader and lower 

 whorls. 



Unfortunately only a single specimen of our species has been found. 

 It was impossible to study the internal whorls in their details and there- 

 fore we can not make more detailed comparisons with other species. 



Number of specimens: 1. 



Age: Lower Turonian (Salmurian), lower horizon. 



VASCOCERAS Choffat 



When Choffat 4 established his new genus Vascoceras he subdivided it 

 into four groups: 1. mono-tuberculated forms with wide umbilicus; 

 2. subglobose forms with rounded umbilical border ; 3. globose forms with 

 angular or subangular umbilical border; 4. multi-tuberculated forms. 

 These groups could be called: 1. Group of Vascoceras Gamai; 2. Group 



'Peron, Amm. du Cret. sup. de PAlgerie, p. 23, pi. 7, figs. 2, 3. 

 2 Pervinquiere, Paleontologie Tunisienne, p. 325, pi. 20, figs. 5, 6. 

 3 Stoliczka, Ceph. Cret. Rocks India, p. 122, pi. 60, fig. 1. 

 Choffat, Especes nouv. ou peu conn., p. 51. 



