380 NEW YORK STATE MUSEUM 



Beloceras iynx the thin, disk-shaped, wide umbilicate shell, and in 

 respect to suture there is an easy gradation from the simple outline of 

 Gephyroceras into that of Probeloceras and Beloceras. Taking this series 

 as a whole, it constitutes in New York the most abundant element of the 

 goniatite fauna, and it is proper to bring it in its entirety into comparison 

 with that group in the Domanik called Gephyroceras, which is by much the 

 most prolific there in expression and individuals. Holzapfel describes 10 

 species of this genus, and in the Naples beds the series now includes eight 

 members. Many of the Domanik species attain striking dimensions and 

 the larger of them (G. rex, G. tschernyschewi) suggest to us the 

 remains of equal size which occur in soft shales in southern Erie county 

 (Pike's creek), but the sutures of which have not yet been ascertained, 

 though they are probably progressed beyond the Gephyroceras stage and in 

 harmony with the prevailing habit in the fauna, namely Probeloceras. 



So far as externals are concerned the Naples fauna, in Gephyroce- 

 ras holzapfel i, Probeloceras lutheri, P. naplesense and 

 Beloceras iynx, will essentially duplicate some of the Domanik species ; 

 and we have noted that the Angola shales of Chautauqua county carry a 

 species indistinguishable from G. dom an i cense in respect to exterior. 

 Its suture is not known ; and, while we have ventured to designate it as 

 G e p h y r. cf. d o m a n i c e n s e, it is with the conviction that, in spite of 

 its external agreement with that species, this suture will prove to be pro- 

 gressed beyond the gephyroceran stage. This agreement in exterior differ- 

 entials amongst so important elements in the two faunas is perhaps the 

 most remarkable of the characteristics common to both. It shows that the 

 integrity of the entire group has suffered no external change throughout its 

 travels, while there has been definite progress internally toward more com- 

 plicated septation. Still further interpreted, it means that the Domanik 

 is the point of geographic departure of this fauna westward, its species con- 

 serving traits which are in part unchanged and in part progressed during 

 the geographic progress of the congeries. 



Turning to the genus Timanites, these shells are closely umbilicated, 



