PALEONTOLOGY OF ONTARIO, 135 



VI. PTEROPODA. 



The only Pteropod which is yielded, so far as I know, by the 

 Corniferous and Hamilton formations of Ontario, is a species of 

 Tentaculites, which occurs in great abundance in the latter. It is 

 nearly allied to T. annulatus, Schloth., and T. ornatus, Sow., but 

 does not appear to be quite identical with either ; and I have in the 

 meanwhile left it unidentified. 



VII. GASTEROPODA. 



The number of Gasteropoda in. the Devonian Rocks of Western 

 Canada is very considerable, and this is especially the case as regards 

 the Corniferous Limestone. By far the majority of specimens, how- 

 ever, occur in the state of casts, with little or none of the original 

 surface preserved, often crushed or mutilated in different ways ; and 

 it is thus often impossible to determine their true affinities, or to 

 decide with certainty to Avhat species they may belong. I have thus 

 been compelled to leave altogether unnoticed a number of univalves, 

 of which nothing definite can be made out with the materials that I 

 possess at present ; whilst the determinations actually recorded must 

 be regarded as for the most part more or less doubtful. The only 

 Gasteropod that has come under my notice from the Hamilton For- 

 mation is a small Platyceras, which m^ay be a variety of P. dumosum. 

 Other species of the same genas occur in the Corniferous Lime- 

 stone, one of these being new, whilst another is the well-knoAvn 

 P. ventricosum, Conrad, and the others are not determinable with 

 certainty. The genus Platyostoma is represented by the familiar 

 P. ventricosa, Conrad ; and there are several apparently new forms 

 which I have referred more or less doubtfully to Strophostylus, 

 Holopea, and Helicotoma. 



List of Devonian Gasteropoda. 



142. Platyceras ventricosum, Conrad (C.) 



143. " intermedium, Hall? (C.) 



144. " sp. (C.) 



145. " sp. (C.) 



146. " uniseriale, Nick. (C.) 



147. " dumosum, var. rarispinum, Hall? (H.) 



148. Plat^-ostonia ventricosa, 'Co?*?-*):;^ (C.) 



149. Strophostylus ? sub-globosus, iVzcA. (C.) 



150. " ? ovatus, Nich. (C.) 



