WHiTEAVES. J FOSSILS OP HAMILTON FORMATION OF ONTARIO. 379 



Not uncommon in the Hamilton Group at Widder and at Bartlett's 

 Mills, near Arkona." Nicholson. 



Fenestelt.a Arkonensis. (Nom. prov.) 



Fenestdla tenuireps, Nicholson. 1S74. Rep. Pal. Prov. Ontario, p. 106, figs. 44, a-h. 

 But probably not F. tcnuiceps. Hall, 1852 (Pal. N. York, vol. II., p. 

 165, pi. 40 D, figs. 2, a, h) which is a fossil of the Clinton and Niagara 

 formations of the State of New York, and Ontario. 



"Common in the Hamilton Formation at Bartlett's Mills, near Arkona." 

 Nicholson. 



Retepora prisca, Nicholson. 



Retepora prisca (Goldfuss) Nicholson. 1874. Rep. Pal. Prov. Ontario, p. 101, figs. 

 38, a, h. 



" Common in the Corniferous Limestone of Ridgeway and Port Col- 

 borne ; also in the Hamilton Group at Bartlett's Mills, near Arkona." 

 Nicholson. 



A specimen of this species, from Ridgeway, has been presented to the 

 Museum of the Survey by Professor Nicholson, but the writer has not 

 seen an authentically named, or very closely similar specimen from the 

 Hamilton formation. H. prisca, Goldfuss, is the type of D'Orbigny's ge- 

 nus Reteporina, but Zittel, in the first volume of his Handbuoh der Palse- 

 ontologie (page 600) makes both Retepora and Reteporina synonyms of 

 Fenestella. 



Polypora Arkonensis, S. A. Miller. 



Pohjpora tubcrculata, Nicholson. 1874. Geol. Mag., N.S., vol. I., p. 162; and Rep. Pal. 



Prov. Ontario, p. 100, figs. 37, a-c. But, according to Ulrich (Geol. 



Surv. Illinois, vol. VIIL, p. 595) not P. tnberculata, Prout, 1859. 

 Polypora Arkonensis, S. A. Miller. 1883. Am. Palaeoz. Foss., 2nd. Ed., p. 316. 



Rare in the Hamilton group at Bartlett's Mills. Nicholson. 

 Ptilopora striata. Hall. 



Ptilopora striata, Hall. 1881. Trans. Albany Inst., vol. X., p. 196. 

 1884. Rep. St. Geologist for 188.% p. 58. 

 1887. Pal. N. York, vol. VI., p. 283, pi. 66, figs. 30-33. 



" West Williams, Ontario, Canada." Hall. 



Trematopora carinata, Hall. 



Tre7iMtopora(Orthopora)carinata,'RaM. 1887. Pal. N.York, vol. VI., p. 179, pi. 55, 



fig. 2 ; and pi. 56, fig. 3. 



" Hamilton group, West Williams, Ontario, Canada." Hall. 



