CANNON BALL MARINE MEMBER OF LANCE FORMATION 537 



the north by a high, nearly level plateau which is capped by the 

 lower fossiliferous sandstone of the Cannonball member. The 

 top of the plateau is approximately 500 feet above and only about 

 2 miles distant from the river. The characteristic badland- 

 forming strata of the lower part of the Lance extend up to within 

 about 100 feet of the top of the plateau but here, as elsewhere, no 

 sharp line of demarkation can be drawn. 



Dr. Stanton has kindly prepared the following statement con- 

 cerning the fauna of the Cannonball member. 



The fauna of the Cannonball marine member of the Lance may now be 

 characterized as a modified Fox Hills fauna. It contains a considerable 

 proportion of undescribed species of Cretaceous affinities, and it is noteworthy 

 that a number of the most common Fox Hills species have not been discovered 

 in this fauna. The list of forms recognized is as follows: 



Nodosaria sp. 



Caryophyllia ? sp. 



Anomia sp. 



Perna sp. 



Crenella sp. 



*Cucullaea shumardi M. and H. 

 tGlycimeris subimbricata (M. and H.) 

 *Leda (Yoldia) scitula M. and H. 

 *Leda equilateralis M. and H. ? 

 *Nucula planimarginata M. and H. 

 JCrassatellites evansi (H. and M.) 



Solemya ? sp. 

 *tLucina occidentalis (Morton) 



Corbicula cytheriformis M. and H. 

 fCj^rina ovata M. and H. 

 *Cyprina ovata var. compressa M. and 

 H.? 



Veniella? sp. 



Callista sp. a 



Callista sp. b 



Tellina? sp. 



Thracia sp. related to T. subgracilis 



Whitfield 

 tTeredo globosa M. and H. 



tTeredo selliformis M. and H. 

 Corbula sp. 

 Entails sp. 

 Scala? sp. 

 Turritella? sp. 

 f *Lunatia concinna (H. and M.) 



Cerithium? sp. 

 J*Anchura americana (E. and S.) 

 Anchura americana (E. and S.) robust 



variety 

 Helicaulax ? sp. 

 t*Cantharus (Cantharulus) vaughani 

 M. and H. 

 *Pyrifusus (Neptunella) newberryi M. 



and H. ? 

 *Fasciolaria buccinoides M. and H. 

 *Fasciolaria (Piestochilus) culbertsoni 



M. and H. 

 *Turris contortus M. and H. 

 Turris sp. related to T. contortus M. 



and H. 

 *Turris minor (E. and S.) ? 

 Cinulia sp. 

 *Cylichna scitula M. and H. ? 



In this list of about 40 forms there are 21 named species and varieties of 

 which 15 (marked *) occur in the Fox Hills, 4 (marked J) occur in the Pierre, 

 and 5 (marked j) were originally described from rocks now known to belong 

 to the marine member of .the Lance. One species, Corbicula cytheriformis, 

 was described from the Judith River formation and is known in the Mesaverde 



