122 



Report of the State Geologist. 



Beyr.), which is restricted to the lower part of the Marcellus shales (lowest 

 middle Devonian). Likewise Agoniatites, abundant in the goniatite lime- 

 stone * of the Marcellus beds 'and occurring sparingly through the higher 

 strata of the Hamilton group, is not yet known to be of greater age. 



In the German Devonian faunas, Tornoceras does not appear so early 

 with reference to these other genera, but it is stated by Frecii f to be 

 present in the lower Devonian limestone of Cabrieres (France) and also to 

 be represented in the lowest Devonian of the eastern Alps (Wolayer Thorl) 

 by two species, Torn, inexpectatum and Tom. Stachei, occurring in association 

 with Anarcestes lateseptattis.% 



We may look upon these facts as essentially the sum of present evidence 

 as to the historical relations of Tornoceras with these simpler genera. They 

 do not justify an assumption that this genus has been directly derived from 

 either Anarcestes or Agoniatites. Tornoceras takes no place in the line of 

 phases in part contemporaneous and in part successive, which we have now 

 seen to constitute the series from Agoniatites through Gephyroceras to Pro- 

 beloceras, Beloceras and Prolecanites. With Parodoceras it is outside this 

 line of development. Its generic characters indicate an accelerated develop- 

 ment firmly established and long continued ; a departure from a more distant 

 source in which the origin of Anarcestes and Agoniatites may also be sought. 



Family Bactritidae, Hyatt. 



Genus Bactrites, G. Sandberger. 



Since the determination by Branco, that a certain specimen from the 

 Wissenbach slates, referred by him to the genus Bactrites, bears an egg- 

 shaped, erect protoconch similar to that possessed by Gromatiies CQmpreswts, 

 Beyrich, and other representatives of the genus Mimogeras, authors generally 

 have inferred a close genetic connexion between Bactrites and the goniatites, 

 by way of Mimoceras and Anarcestes. The additional evidence pertaining 

 to the character of the early stages in this genus, which was brought out by 

 the writer in the American Geologist, for July, 1894§, and which will be here 

 • presented with amplification, does not fail to confirm this inference, while it 



* This well marked horizon which has long been distinguished by this term, would be more precisely designated by the 

 name Agoniatites limestone, as its characteristic species is the Agon, expansns, Vanux»m. The adoption of this term is in 

 accordance with the best usu.ige and is the more justifiable becaus ! of the occurrence of "goniatite limestones " at vari- 

 ous horizons In the Devonian and Subcarboniferous. 



tZeitschr. d. d. geolog. Gesellsch., vol. xxxix, p. 406, 1887. 



X Ibid. p. 73 !, pi xxviii, fig i. B-ll. 



§The Early Stages of Bactrites, op. cit. vol. xiv, p/>. 37-43, pi. 2. 



