GUELPH FAUNA IN THE STATE OF NEW YORK 5 1 



specimens, which were identified with qualification by Hall with the Clinton 

 form of his species. It differs to some extent in possessing a slight depres- 

 sion extending forward from the umbo, which is not mentioned in the 

 description of M. subalata. 



GASTROPODA 



BELiisRopHON Montfort. 1808 

 Bellerophon shelbiensis sp. nov. 



Plate s, fig. 13-19 



Bucania stigmosa? (Hall) Whiteaves, Paleozoic Fossils. 1884. v. 3, pt 1, 



p. 34, pi. 5, fig. 3, 3a; pi. 8, fig. 4 

 Not Bucania stigmosa Hall, Paleontology of New York. 1852. 2:92, pi. 28, 



fig. 8, 8a-e 



Dr Whiteaves has figured from the Guelph of Gait internal casts of a 



symmetric shell which he refers to as Bucania stigmosa? Hall. With 



regard to these he says : 



These agree perfectly with similar but better preserved casts from the 

 Niagara formation at Grimsby Ont., in the museum of the survey, which 

 have been identified with B. stigmosa by E. Billings, but in the absence 

 of any knowledge of the shell of the Gait specimens their determination 

 must be regarded as doubtful. 



A considerable number of similar casts from Shelby leaves no doubt 

 that this form is well distinguished from Hall's Clinton species, Bucania 

 stigmosa, for, besides attaining a size thrice as large, it distinctly differs 

 in the cross section of its whorls, which are more convex on the dorsal and 

 more deeply concave on the ventral side, the whorls embracing somewhat 

 more than in the Clinton species. 



Diagnosis. Shell somewhat below medium size, having an average 

 diameter of 15 mm and rarely attaining more than 25 mm; consisting of 

 about three volutions which increase but slowly in size ; whorls embracing 

 about one third of the hight, lowly subtriangular in cross section, with a 

 dorsal carina which, bearing the slit-band, becomes more prominent as 

 growth advances. The sides are convex, full or evenly rounded in young 

 stages, becoming more gently convex in later growth, abruptly sloping to 



