27 



GASTEKOPODA. 



Genus Cassiope Coquand. 



Cassiope Whitfieldi {sp. nov.) — Shell large, elongat-econical, um- 

 bilicate ; volutions apparently about twelve, ijrominent, and promi- 

 nently angular below the middle of the visible portion, slightly con- 

 cave from the prominent revolving angle to the suture below, also 

 very slightly and somewhat irregularly concave from that angle to the 

 suture above. A little below the suture there is a rather small, shallow 

 furrow, with its borders, above and below, raised into more or less dis- 

 tinct, revolving ridges. 



Upon the under side of the last volution, which is rather strongly 

 convex, there are three small revolving ridges, one of them bounding 

 the umbilicus, the other two near each otber above the middle of the 

 space and continuous to the apex of the shell. It is between the two 

 last-named ridges that the upi)er edge of each succeeding volution joins 

 the preceding one. Umbilicus moderately large and deep ; aperture 

 subovate in outline; outer lip sinuate, having a broad, shallow notch 

 above its middle, projecting and rounded abruptly into the umbilicus 

 below. 



Surface marked by more or less strong, undulating lines of growth, 

 fine, revolving lines absent or obscure. 



Diameter of the last volution of our largest specimen, nearly four and 

 a half centimeters ; the full height of the same, when entire, must have 

 been not far from eleven centimeters. 



This shell more nearly resembles Turretella Mortoni Conrad in general 

 aspect than any other described species; but the presence of an umbil- 

 icus separates it generically from that shell. 



Dedicated to Mr. R. P. Whitfield, the accomplished palaeontologist of 

 Albany, N. Y. 



Position and locality. — Cretaceous strata, at the head of Le Verken 

 Creek, and also in Pace's Caiion, Utah. 



