COPE.] PALEONTOLOGY CSETACEOUS PERIOD APPENDIX. 455 



APPENDIX. 



Descriptions of neic moUuslcs from Cretaceous heds of Colorado, hy T. A. 



Conrad. 



I add here some determiuatious, by T. A. Conrad, of mollusks of Cre- 

 taceous age obtained near Denver and in the South Park. 



HELICOCERAS, d'Orb. 



H. VESPEETINUS. — Sinistral, gradually tapering; ribs prominent, 

 often placed irregularly as regards distance from each other, gradually 

 thickening toward the back, which has two rows of tubercles; back 

 flattened on the large part of the shell, and gradually rounding on the 

 smaller. 



Locality. — Seven miles south-southeast of Fairplay. 



In the small specimen of rock containing this fossil are two speci- 

 mens of the same and two of Ftychoceras. 



ANCHUEA, Conrad. 



A. BELLA. — Subfusiform ; spire elevated ; volutions convex, with ob- 

 lique, subacute, curved,* longitudinal ribs, crossed by regular, fine striae; 

 suture deeply impressed ; last volution with two distant, angular, revolv- 

 ing ridges, the upper one largest and extending to the end of the pro- 

 jecting lip ; above this angle, the ribs are less prominent and distinct than 

 on the spine, and disappear at the lower revolving angle ; lip upturned 

 toward the extremity and acute at the end; lower margin entire ; beak 

 short, narrow, acute. 



MEEKIA, Gabb. 



M. BULLATA. — Subglobose, inequilateral ; anterior side short, com- 

 pressed, acute at the end ; summits very prominent ; umbo inflated. 

 This smooth little species is proportionally much shorter and the um- 

 boues more inflated than in M. sella, Gabb. The anterior side is shorter 

 and more acute. 



Locality. — Trout Creek, near Fairplay. 



FTYCHOCERAS, d'Orb. 



P. AHATUS. — Larger branch having prominent, slightly oblique, sub- 

 undulated, compressed ribs, subacute on the margin; body slightly 

 swelling on the back toward the base, where the ribs become fine and 

 close; smaller branch ribbed obliquely in a downward direction. 



Locality. — Trout Creek, near Fairplay. 



There are two rows of very small tubercles on the flattened back of 

 this species. 



HAPLOSCAPHID^. 



The genus Haploscaplia, described in a former volume of these reports, 

 is not, as I thought at the time, a member of the family Eudisttc, but 



