GUELPH FAUNA IN THE STATE OF NEW YORK 97 



side of the septae is directed toward the body-chamber," a structure which 

 would indeed be quite unique among the Cephalopoda. Cyrtoceras 

 r e v e r s u m is described as occurring in "the lower beds of the Niagara 

 limestones at lighthouse station on the G. T. R." It may, therefore, occur 

 at a similar horizon as the lower Shelby form. 



Poterioceras sp. 



Plate 13, fig. 13-16 



A single living chamber, found in the lower Shelby dolomite, differs 

 so materially from those of the associated P. sauridens that we are 

 constrained to note it separately. The living chamber is quite evenly 

 rounded and plump, the flattening of the dorsal side but slightly devel- 

 oped. The section of the living chamber and also of the aperture is nearly 

 circular. The ventral and lateral surfaces are regularly and evenly con- 

 tracted from the middle of the chamber toward the aperture. The 

 siphuncle is marginal (subventral) and highly nummuloidal. The camerae 

 are not preserved, but, judging from the siphuncle, they were shallow and 

 the septa but slightly convex. The cast shows traces of transverse striae, 

 presumably growth lines. 



PROTOPHRAGMOCERAS Hyatt. I9OO 



Protophragmoceras patronus sp. nov. 



Plate 19, fig. 1, 2 



A very robust, moderately tapering, strongly and regularly curved 

 shell. The arc of the outer curvature is 190 mm long and its chord is 

 165 mm ; the inner curve is about 140 mm long and its chord measures 90 

 mm. Section in the earlier part of the septate portion broadly elliptic, 

 the major axis being the dorsoventral ; the living chamber and mature part 

 of the cone have an oval or roundly triangular section, the outer (ventral) 

 side being very broadly rounded, the inner side narrowly so and the lateral 

 parts nearly flat, sloping to the dorsal ridge. 



Camerae very deep, last septa being 21 mm apart on the ventral side 

 and about 8 mm on the dorsal side ; sutures transverse with a broad, low 

 saddle extending the full width of the venter. Depth of septum almost 



