54 NEW YORK STATE MUSEUM 



sented in the upper Silurian." The spirally ribbed later species are united 

 by this author under a new generic term, Bucanopsis. As these forms do 

 not differ from Bellerophon in other features than the cancelation of the 

 surface, the genus is placed among the Bellerophontidae. To Bucanopsis 

 are referred the well known Hamilton species Bell, leda and B. lyra. 

 If our Guelph species should prove to be ornamented with spiral lines, it 

 would also be referable to Bucanopsis. 



TKKii ak.notis Hall. 1868 (emend.) 

 Trematonotus alpheus Hall 



Plate s, fig. 20-23 ; plate 6, fig. 1-0 



Tremanotus alpheus Hall, separately printed in advance for N. Y. State Cab. 



Nat. Hist. 18th An. Rep't. 1865. p. 43 

 Tremanotus al ph eu s Hall, N. Y. State Cab. Nat. Hist. 20th An. Rep't. 1867. 



P- 347, pl- IS, ng- 23, 24 

 Tremanotis alpheus McChesney, Chicago Acad. Sciences. Trans. 1859. v. 1, 



pl. 8, fig. 4a, b 

 Bellerophon (Bucania) p er f o rat u s Winchell & Marcy, Boston Soc. Nat. 



Hist. Mem. 1866. v. 1, no. 1, p. 108 

 Tremanotus alpheus Whitfield, Geol. Sur. Ohio. v. 2, Paleontology, p. 145, 



pl. 8, fig. 1 

 Tremanotus a n g u s t a t u s Whiteaves, Paleozoic Fossils. 1895. v. 3, pt 2, p. 70 

 Not Bucania chicagoensis McChesney, Description of New Species of Fos- 

 sil from Paleozoic Rocks of Western States (advance extr. Chicago Acad. Sci. 



Trans, v. 1). 1859. p. 69, pl. 8, fig. 5a, b (plate published at a later date) 

 Probably Bucania angustata Hall, Paleontology of New York. 1852. 2:349, 



pl. 84, fig. 7a-d 



Of this remarkable type of symmetric gastropod structure, three speci- 

 mens have been observed in the material from the Guelph horizon at Roch- 

 ester, one from Newman's quarry, one among the fossils from the same 

 horizon (upper Shelby) at Oak Orchard creek and not less than 100 internal 

 and external molds in the collection from the lower Shelby bed. Two of 

 the Rochester specimens are in a fair state of preservation, and most of the 

 lower Shelby examples are excellently preserved, much better than are the 

 originals of the species, as they retain the surface markings and the aper- 



