LOGAN : FREEZE-OUT HILLS OF WYOMING. 125 



Cf( HI jttonectes exteniKittis Meek and Hayden. 



Shell medium size, ovate or suboval in outline. The hinge line is 

 straight, equaling in extent nearly one-half the length of the shell. 

 The ears are large and triangular ; the margins of the posterior one 

 slopes abruptly backward to the body of the shell. The beaks are 

 small, not projecting above the hinge line, and somewhat sharply 

 rounded. The surface of the shell is marked by fine radiating stria?, 

 which diverge from the median line and converge toward the lateral 

 border ; also by concentric stria?, which cross the former at right 

 angles. 



Dimensions: Length, 30 mm.; width, 22 mm.; height, 8 mm. 



Geological horizon : These fossils occur in the greenish-colored 

 sandstone of No. 14 of the section. 



Localit}' : The Freeze-out Hills, Wyoming ; also reported from 

 Dakota. 



Remarks : C. curvatus, described by Whiteaves from the Jurassic 

 fauna of the Queen Charlotte islands, is probably a synonym of 

 C. extenuatus. The following forms are recognized in both faunas : 

 Belemnites densus, B. curtus, Astarte packardi, Pleuromya suh- 

 compressa, Avicula {Oxytoma) mucronata, Gryphcua nehrascaensis, 

 and Camptonectes extenuatus. 



Cardinia irt/oinhH/eiisis. n. sp. Plate XXV, fig. 8. 



Shell large, convex, subquadangular, length more than twice the 

 width. The hinge line is long and straight. The posterior border 

 forms an acute angle with the ventral border, which is long and 

 straight. The anterior border is rounded. The contour of the shell 

 forms a rounded escarpment, which extends from the umbonal region 

 to the jjosterio-ventral border angle. The test of the shell is thick. 

 The surface is ornamented with prominent concentric lines of growth- 

 Dimensions : Length, 90 mm.; width, 35 mm.; height, 8 mm. 

 Geological horizon : A few representatives of this form were found 

 in stratum No. 13, in which they were not abundant. They occur 

 with the fossils already mentioned as belonging to that horizon. 

 Locality : The Freeze-out Hills, Wyoming. 



Remarks : This is a rare form in the Jurassic fauna, as very few 

 specimens were collected. The genus seems well represented in the 

 European fauna of the Jura. 



Psendoiuoiiotis rui-ta Hall. Plate XXX, fig. 5. 

 Shell (left valve) of medium size, obliquely saborbicular, unequi- 

 valve, convex. The beaks are obtusely pointed and prominent, ex- 

 tending above the cardinal line, and having the apex slightly incurved. 

 The hinge line scarcely equals half the length of the shell. The an- 



