34 Permo-Carboniferoiis Ammonoids of the Glass Mountains 



both faunas are synchronous. The rest of the genera in our zone of 

 Waagenoceras confirms this opinion, especially Medlicottia, Gastri- 

 oceras of the G. Zitteli group, Paraceltites, Adrianites and ''Stacheo- 

 ceras. Our fauna is much poorer ixi species than that of the Sosio beds 

 and that explains, perhaps, why a number of genera that occur in the 

 Sosio beds have not yet been found in the Word formation. The 

 principal ones of these genera are: Hyattoceras, Popanoceras (possi- 

 bly represented by some forms that have been taken for Stacheoceras) , 

 Propinacoceras, Parapronorites, Sicanites, Daraelifes, Thaiassoceras, 

 Doryceras. and Clinolobus. While many of these genera are very rare 

 also in the SiciHan deposits, the absence of some of them, such as 

 Hyaitoceras, Popanoceras, Propinacoceras and Thaiassoceras, is some- 

 what surprising; although some of them may be found in the future. 

 If, according to Gemmellaro, Hyattoceras had not been found to- 

 gether with Waagenoceras, we might suppose that it is represented 

 in the Glass Mountains by Perrinites; but this latter genus always 

 occurs below the strata with Waagenoceras! 



In another chapter we have tried to show that the fauna of the zone 

 of Waagenoceras is intimately related to that of the zone of Perrinites. 

 At the same time it appears that the fauna of this latter zone does not 

 show very great differences from that of the Sosio beds, although a 

 comparison is made difficult by the reduced number of species col- 

 lected until now in the zone of Perrinites. The following table will 

 explain those relations : 



SPECIES FROM THE LEONARD FORMATION CORRESPONDING FORMS PROM OTHER 



OF THE GLASS MOUNTAINS LOCALITIES 



Medlicottia Whdtneyi n. sp. M. bifrons Gemm. Sosio beds 



Gastrioceras altudense n. sp. G. Waageni Gemm. Sosio beds 



Perrinites vidriensis n. sp. Hyattoceras (?) Sosio beds 



Perrinites compressus n. sp. ^ 



Paralecanites altudensis n. sp. 



Perrinites is so nearly related to Hyaitoceras that we might take 

 it for its precursor, but unfortunately the evolution of the suture of 

 the latter genus is unknown, so that we do not know if it passes- 

 through some stage similar to the suture of Perrinites. We might also 

 suppose that this latter genus vicariates for Hyattoceras, and that the 

 zone thus simply represents a certain phase of the Sosio beds. 



