130 KANSAS UXIVERSITY QUARTERLY. 



transverse section by thin, closely arranged septa, which become more 

 widely separated with increased distance from the phragmacone. The 

 apex of the cone-shaped alveolar cavity is subcentrally located in the 

 adult forms but is central in young individuals. The species varies 

 much in size but retains the same general form. 



Dimensions: Length of specimen, 140 mm.; length of phragma- 

 cone, 50 mm.; diameter, 20 mm. 



Geological horizon : This species occurs in great abundance in No. 

 13 of the section. It is found associated with Pleuromya subcom- 

 pressa, Astarte packardi, Pinna kingi, Goniomya montanaenfiis, etc. 



Locality : Freeze-out Hills, Wyoming. Black Hills, Dakota, and 

 elsewhere. 



Remarks : This is by far the most abundant s^jecies in the Jura of 

 Wyoming. In certain outcrops in the Freeze-out Hills the slopes of 

 the hills are so completely dotted with them as to leave scarcely a sin- 

 gle square foot without one or more representatives. From these out- 

 crops it is possible to gather bushels of them. Their persistence in 

 the stratum in which they occur make it a good guide in the study of 

 the stratigraphy. B. skidgatensis is undoubtedly a synonym of B. 

 densus, as all of the forms figured by Meek have the same form as 

 Whiteaves's species. 



Belemnites ctirtus. n. sp. Plate XXIX, figs. 4, 5; plate II, fig. 3. 



Guard large size, thick, abruptly pointed, subquadrangular at the 

 distal end, while it is more cylindrical toward the proximal portion. 

 The point of the guard is extremely blunt. The guard substance is 

 dense, dark colored, and of prismatic structure. 



Dimensions: Length, 120 mm.; diameter, 30 mm. 



Geological horizon : No. 13 of the section has furnished a few 

 specimens of this siDecies. 



Locality : The Freeze-out Hills, of Wyoming. 



Remarks : Such a radical ditference in general form seems to ex- 

 clude the possibility of this form belonging to Belemnltes densus, 

 while its symmetry would indicate that its ditference of form was not 

 due to an accident of growth. 



This form was never figured by Meek under the name B. densus, 

 but the form so described is longer and more slender. The latter I 

 take to be the same as B. skidgatensis Whiteaves. This is one of the 

 species which link the Jura of Wyoming with that of Queen Charlotte 

 islands. 



Asfcrfas <liihinm Whitfield. Plate XXV, fig. 3. 



A single imperfect specimen collected from the crinoidal sandstone 

 horizon possesses characters very similar to those of the above-named 

 species. The specimen is somewhat weathered, and, as a result, its 



