268 NEW UPPER CAMBRIAN FOSSILS WALCOTT. 



Formation and locaUfi/.—UpiKir Cambrian Sandstone (Middle horizon) 

 at Spofford's Bluff, Wisconsin. Collector, Dr. Cooper Curtice, 

 Nat. Mus. Cat., Invert. Foss., -:3843. 



Platyceras hoyti sp. dov. 



Plate XX, Fig. 8. 



Shell small, depressed, making about three volutions, the interior 

 below the plane of the outer volution. Volutions eontiguous throughout 

 their extent, expanding gradually to the somewhat compressed, more 

 rai)idly expanding outer whorl. Aperture unknown. 



Outer surface of shell marked by line concentric stria', and the inner 

 surface by longitudinal stria^ 



This species differs from the associated P. minutissimum in the form of 

 the whorls and surface characters. The longest specimen has a trans- 

 verse diameter of 4""". 



Formation and locality. — Upper Cambrian limestone, 4 miles west of 

 Saratoga Springs, New York. C. D. W,, collector. 



Nat. Mus. Cat., Invert, Foss., 2384(3. 



Platyceras texanimi sp. nov. 

 Plate XX, Fig. 5. 

 Cnpnlus sp. ? Sliuiriard, 18G1, Am. Jour. Set., 2d ser., vol. 32, p. 221. 



Shell small, making about two (1) volutions, the interior below the 

 plane of the outer volution but not quite on the median line. Volutions 

 api)areutly contiguous throughout their extent, the inner, or spire, small, 

 gradually ex[)anding; body volution strongly carinate upon the dorsum, 

 and expanding gradually to the large subelliptical outer portion. Aj)er- 

 ture unknown. 



This s])ecies is more nearly related to P. minnt ssimtmi of the Potsdam 

 of New York than to P. Iioyti. The longer specimens have a diameter 

 of 7'""' across the body whorl. 



Formation and locality. — Upper Cambrian Limestone, of Packsaddle 

 Mountain, Burnet County, Texas. Collector, C. D. W. 



Nat. Mus. Cat., Invert. Foss., 23845. 



Genus TROCHUS Liun. 



Trochus? saratogensis sp. nov. 



Plate XX, Fig. :5. 



Shell trochiforme, sinistral, broadly conical with about four slightly 

 convex whorls; base concave; umbilical surface sloping inward from 

 the angle produced by its union with the outer curvature of the body 

 whorl ; umbilicus rounded and of medium size ; aperture obliquely sub- 

 ellii)tical; periphery unknown. Surface marked by a few fine stria3 of 

 growth. 



