310 REPORT UNITED STATES GEOLOGIC AE SURVEY. 



laterally, apparently occupying more than half the under surface of the 

 shell ; outer lip moderately thin, smooth, or at least not crenulate. Sur- 

 face marked by ordinary lines and undulations of growth, and upon the . 

 middle portion of the anterior half by live or six narrow, slightly raised, 

 obscure, radiating ribs, with spaces between them a little wider than 

 the ribs. In some cases there are also other obscure radiating hues 

 upon the anterior flanks of the shell. 



Length, 11 millimeters ; breadth, 8 millimeters ; height, 5 millimeters. 

 Some examples in the collection are larger, but none of them quite equal 

 in size the larger examples of the typical forms of the species. 



This variety, although perhaps connecting the typical forms with IST. 

 ( V.) carditoides Meek, differs from it in the number and character of its 

 costse, the proportions of the shell, and its smaller size. At one time I 

 thought, as did also Mr. Meek, that this variety might prove to be 

 specifically distinct from the typical forms of JSf. ( V.) patelliformis, but 

 study of collections since made at the typical locality shows that inter- 

 mediate forms exist, associated with this variety and. the typical forms 

 in the same layer. 



" Position and locality. — Cretaceous strata, equivalent with the upper 

 part of the Colorado Group or base of the Fox Hills Group, Coalville, 

 Utah." 



Genus EFSPIBA Agassiz. 



EUSPIRA. COAEVTLLENSIS White. 

 Plate 4, figs. 2 a and 6. 

 Lunatia coalvilJensis White, 1876, Powell's Eep. Geol. Uinta Mts. p. 122. 



Shell subglobose ; spire small, conical, acute, but not much extended ; 

 volutions about eight when the apex is entire, last one inflated, and, when 

 adult, extended a little in front, and also posteriorly, near the border of 

 the aperture ; aperture obliquely ovate-semilunar, somewhat abruptly 

 rounded anteriorly ; callus of the inner lip apparently not much thickened, 

 but thicker anteriorly than posteriorly ; columella rimate or almost solid 

 and nearly covered by the callus of the inner lip, which seems not to be 

 so closely appressed against it as it is against the body- volution farther 

 back. Surface marked by the ordinary lines of growth. The figures on 

 plate 4 are restorations of this species, all the numerous examples in the 

 collections being crushed, except one or two sandstone casts. The ex- 

 amples being somewhat numerous afford a view of all the features shown 

 by the figures. 



Length, from the apex to the anterior end of the aperture, about 4 cen- 

 timeters ; breadth, across the aperture and body- volution, about 3 £ cen- 

 timeters. 



In general aspect this species closely resembles E. rotundata Sowerby 

 sp., as figured and described by Stoliczska (Palseontologia Inclica, vol. 

 II, p. 303, pi. xxi, figs. 9 and 9 a), but it differs in its somewhat more 

 acute spire and more elongate aperture ; and in some of our examples 

 there is an extension of the apex of the spire similar to that shown by 

 Stoliczska (loc. cit. figs. 7 and 8), in E. pagoda Forbes. Perhaps no 

 generic distinction should be made between those Cretaceous forms which 

 are usually referred to Lunatia and those which have been referred to 

 Euspira; but for the present I prefer to retain the latter name for those 

 forms which have a small prominent spire and less compact form than 

 those shells have which are regarded as typical of Lunatia. 



Position and locality. — Cretaceous strata, upper portion of the Colo- 

 rado Group, or base of the Fox Hills Group j Coalville, Utah. 



