162 COLORADO FORMATION AND ITS INVERTEBRATE FAUNA, [bull.106. 



Length of the larger specimen, 10 mm ; breadth, 5""". 



This species is closely related to Actcvon subcllipticus M. & II., 

 which occurs in the Fort Pierre shales of Dakota. It has a larger 

 number of whorls and fewer revolving strioe, the form of the aperture 

 is slightly different, and the body volution is more ventricose. 



Locality &nd position. — In the Puguellus sandstone, Poison canyon, 

 Huerfano park, Colorado, represented by three specimens. 



BULLID^E. 

 Genus H AMINE A Leach. 



H AMINE A TRUNCATA 11. Sp. 



PI. xxxiv, Figs. 9-11. 



Shell rather large, thin, subcylindrical ; whorls two and a half or 

 three, the last one very large and gradually expanding to the anterior 

 end, where it is squarely truncate; spire depressed, not projecting 

 above the last whorl ; sutures channeled. Surface smooth and polished, 

 with faint wrinkles and lines of growth and very obscure traces of re- 

 volving striae. Possibly the thin outer layer of shell bearing the revolv- 

 ing stria? has been exfoliated. The aperture is subtriangular, being 

 narrow and acute behind and very broad in front. The outer lip is free 

 from the preceding whorl for some distance, leaving a moderately deep 

 narrow slit, below which it is almost straight to the front, where it is 

 abruptly rounded into the straight anterior border. 



Length of the largest specimen, 23 ,m "; greatest breadth, 18""". 



The depressed spire, the smooth surface, and the square-cut anterior 

 end are the distinctive features of this species by which it may be sepa- 

 rated from all the described Cretaceous forms known to me, though a 

 number of recent species resemble it more closely in these respects. 



Locality mid position. — In the Pugnellus sandstone, Poison canyon, 

 Huerfano park, Colorado. Eepresented by three specimens. 



AURICULID^l. 



Genus MELAMPUS Montfort. 



Melampus? ? 



Melampns? ? White, 1880, Ann. Rept. U. S. G col. Snr. Terr, for 1878, p. 25, PI. 



19, Fig. 6a ; 1883, 3d Ann. Rept. U. S. Geol. Snr., p. 444,'P1. 5, Fig. 17. 



This species, which has never been described or named on account 

 of lack of sufficient material, was found in the lowest fossiliferous beds 

 of the Cretaceous section at Coalville, Utah. Only one specimen has 

 yet been found. 



