GUELPH FAUNA IN THE STATE OF NEW YORK 59 



Bucania angusta 1 (in error for angustata), which probably is a 

 synonym of T. alpheus, as stated above. Hall also 2 mentions the 

 occurrence of Bucania angustata at Racine, stating that the speci- 

 men is indistinguishable from the species occurring at Gait. The early 

 appearance of this form in the Racine beds of Wisconsin seems to us quite 

 significant in view of the abundant appearance of T. alpheus in the 

 lower Shelby dolomite. 



DIAPHOROSTOMA Fischer. I 885 



Diaphorostoma niagarense Hall (sp.) 



Plate 10, fig. 14-16 



Platyostoma niagarensis Hall, Paleontology of New York. 1852. 2:287, 

 pi. 60, fig. i a v 



Two very young specimens from Rochester and four equally small 

 ones from the upper Guelph at Shelby, exhibit in profile, shape of volu- 

 tions, aperture and surface markings, the characteristic features of D. 

 niagarense. The largest of these specimens possesses a broad, shallow 

 depression on the middle of the body whorl, where the growth lines are 

 distinctly sinuate. 



This form occurs in various exposures of the Rochester shale within 

 the State of New York, and also in more robust development at Waldron 

 Ind. It is not reported from the Guelph formation, nor has it been recog- 

 nized from the Coralline limestone of eastern New York. 



POLKUMITA nom. nov. 



In 1876 Munier-Chalmas introduced 3 the generic term Oriostoma 

 (-Horiostoma) for certain French Lower Devonic shells which have been 

 more fully explicated by Oehlert and Barrois. Lindstrom," after com- 

 parison of the Gothland shells with the French species regarded both 

 congeneric, admitting however a dissimilarity in the abundant presence 



'Geul. Wisconsin, 2:375. 



"N. Y. State Cab. Nat. Hist. 2oth An. Rep't. 1867. p. 346. 



3 Jour, de Conchyliologie, 16 : 103. 



*The Silurian Gastropoda and Pteropoda of Gotland. 



