284 UNITED STATES GEOLOGICAL SURVEY OF THE TERRITORIES. 



C i 11 u I i a ( O ! i £ © p t y c h a ) concinna, H. & M. (sp.). 

 Plate 31, figs. 6 bis, a, b, c. 



A, loon concinnus, Hull and Meek (1834), Mem. Am. Acad. Arts and Sci., Boston, V (n. s.), 390, pi. iii, fig. 4. 

 Ardlana subglobosa, Meek and Hayden (1856), Proceed. Acad. Nat. Sci. Philad., VIII, 64. 

 Avellana concinna, Meek (1859), Hinds' Report Saskatchewan and Assiuib. Exped., 184. 

 Cinulia concinna, Meek and Hayden (1860), Proceed. Acad. Nat. Sci. Philad., XII, 425. 



Shell small, subglobose; spire very short: volutions four, increasing 

 very rapidly in size, the last one forming nearly the entire bulk of the shell; 

 those of the spire slightly convex ; suture distinct ; surface ornamented by 

 small, punctate, revolving striae, generally less than the spaces between, and 

 numbering about twenty-six to twenty-eight on the body-volution; aperture 

 sublimate or auriform, widest below the middle, and narrowing upward ; 

 reflexed and smooth outer lip forming only a narrow, moderately-thickened 

 band ; inner lip rather thick all the way up, and wider where it supports the 

 very prominent, transverse, tooth-like fold, or plication, below ; margin of 

 aperture faintly sinuous below. 



Length, 0.30 inch ; breadth, 0.28 inch ; length of aperture, 0.22 inch ; 

 breadth of same, 0.10 inch. 



The original type-specimen of this species seems to have been an imma- 

 ture individual, that had not developed the thickened marginal rim of the lip, 

 as we now know from others that this character is always present in adult 

 individuals, unless in cases where the lip has been broken. This being the 

 case, it cannot, of course, be properly retained in the genus Actceon, but falls 

 within the genus Cinulia. I know of no species so nearly related in its spe- 

 cific characters as to render a critical comparison necessary. 



Loca/iti/ and position. — Moreau River, Dakota ; from the Fox Hills 

 group of the Upper Missouri Cretaceous series. I have also seen specimens 

 of it from the Yellowstone River of Montana, and others in Professor Hinds' 

 collections, from about the same horizon on the Assiniboine River, British 

 America. The original type-specimen was found on Sage Creek, Dakota, in 

 the upper beds of the Fort Pierre group of the Cretaceous series. 



