whtte.1 PALEONTOLOGY CKETACEOUS FOSSILS. 291 



valves from the front. Surface ornamented by small, regular, concen- 

 tric ridges, or strong lines and furrows, both of which are more distinct 

 on the right valve than on the left, where they are sometimes obsolete. 



" Length of largest specimen seen, 0.50 inch ; height, 0.32 inch ; con- 

 vexity, 0.25 inch. 



"Locality and position. — Near Cedar City, Southern Utah, from coal- 

 bearing Cretaceous beds, apparently belonging to the same horizon as 

 the lower part of the coal series at Coalville. It occurs in great num- 

 bers, associated with Turritella coalvillensis and other forms apparently 

 identical with Coalville species." 



This species, as pointed out by Mr. Meek, closely resembles some of the 

 varieties of C.perundala Meek & Hayden, but it differs sufficiently from 

 any other form yet found in any marine Cretaceous strata. Some small 

 specimens of apparently the same species were found among the fresh- 

 and brackish-water Cretaceous forms at Carleton's coal mines near Coal- 

 ville, but the typical examples are associated with marine forms. 



Genus CAEDIUM Linnseus. 



Caediuh paupeecultjim Meek. 



Plate 9, fig. 3 a. 

 Cardium pduperculum Meek, 1872, An. Eep. U. S. Geol. Surv. Terr, for 1870, p. 306. 



The following is Mr. Meek's description of this species, and as no ad- 

 ditional examples of it have been collected, no further determinations 

 have been made concerning its characters and relations. The illustra- 

 tion, fig. 3 «, plate 9, was drawn by Mr. Meek shortly before his death, 

 and represents one of the better-preserved examples in the collection : 



" Shell small, very thin, rather oompressed, subovate or subcircular ; 

 beaks moderately prominent and nearly central ; surface ornamented by 

 about thirty regular, simple, distinctly defined, radiating costse, which 

 about equal the intermediate furrows, and (owing to the thinness of the 

 valves) are well defined internally, and thus impart a plicated or crenated 

 character to the margins; crossing these are numerous very regular, 

 well-defined, delicate marks of growth, that are usually less distinct on 

 the posterior third, but give a neatly crenulated appearance to the costse 

 further forward. 



" The specimens of this little shell are rarely more than about 0.50 

 inch in diameter, and are all more or less flattened or otherwise distorted. 

 Sometimes they are distorted by antero-posterior pressure, so as to pre- 

 sent somewhat the appearance and outline of a Lima, being higher than 

 wide, and more or less oblique ; while in other examples they are dis- 

 torted by vertical pressure, so as to present little or no obliquity and to 

 show a greater antero-posterior diameter than height. I have not seen 

 the hinge, but some impressions in the matrix show that it has anterior 

 and posterior lateral teeth like those of Cardium. It, however, does not 

 properly belong to the typical section of that genus. 



"Locality and position. — Fort Benton Group, or No. 2 of the Upper 

 Missouri Cretaceous series, at Oil Springs, 20 miles west of FortBridger, 

 Wyo." 



Carditbx trite (sp. nov.). 



Plate 5, figs. 4 a and i. 



Shell broadly subovate or suborbicular, height and width about equal; 

 valves gibbous, regularly arching from beak to base ; median portion 



