WHiTEAVES.] FOSSILS OF HAMILTON FORMATION OP ONTARIO. 113 



It is true that in two of the specimens from Arkona, though appar- 

 ently not in all, the beak of the ventral valve is very faintly ti-uncated, 

 but DeVerneuil represents the beak of the coiTesponding valve of the 

 shell which he calls Productus membranaceus and which Davidson 

 places in the synonymy of S. productoides, as distinctly truncated. 

 Prof. Hall states that " on the authority of il. de Verneuil, the Stro- 

 phomena pustulosa has been referred to the Productus (Strophalasia) 

 Murchisonianus o{ De Komck,' ' or, in other words, that De Verneuil 

 thinks P. truncata, Hall, is synonymous with the shell which Davidson 

 calls S. productoides, and to the writer it seems that de Verneuil's figu- 

 res of Productus membranaceus would do very well for P. truncata. On 

 the other hand, Mr. C. D. Walcott considers that the two shells, i. e., 

 P. truncata and S. productoides, " present but very few characters in 

 common." 



Chonetes carinata, Conrad. 



Stroplioniena carinata, Conrad. 1842. Journ. Ac. Nat. So. Phil., vol. VIII., p. 2.j7. 



" syrtalix, Conrad. " lb., p. 254, pi. 14. fig. 1. 



Chonetes cronnta, Hall. 1867. Pal. State X. York, vol. IV., \A. 1, p. 13.3, pi. 21, 



figs. 9-12, incl. 

 Chonetes carinata, S. A. Miller (as of Conrad). lt>77. Am. Pal. Fos3., p. 108. 

 Chonetes coronata, Whitfield. 1882. Geol. VViscons., vol. IV., p. 327, pi. 2.5, fig. 16. 



Bartlett's Mills, near Arkona, Eev. J. M. Goodwillie, 1882 : one per- 

 fect and well preserved specimen showing the exterior of both valves. 



Professors James Hall and E. P. Whitfield both think that the speci- 

 fic name of this .•5hell should be written coronata rather than carinata. 

 The former doubtless would be the more appropriate of the two. 



StREPTORHYNCHUS PERTERStJM, Hall. 



Orthis perversa, Hall. 1857. Tenth Rep. N. York St. Cab. Nat. Hist., p. 97. 

 Orthigina alteimata, Hall. 1860. Thirteenth Rep. N. Y. St. Cab. Nat. Hist. 

 Streptorhynchus perversa. Hall. 1867. PaL State N. York, vol. IV., pt. I, p. 72, pi. 9, 

 figs. 13-17 and fig. 26. 



Lot 24, Concession 3, Township of Bosanquet, J. Eichardson, 1859 : 

 one small but perfect specimen which was identified with this species 

 or variety many years ago by Mr. B. Billings. 



Professor Hall regards S. perversum as only a varietal form of 

 S. Chemung ense, Conrad. 



