128 CAEBONIFEliOUS PERIOD. 



X 



England by that gentleman, from collections made in Punjab, India, many- 

 specimens of oiu- shell are found to be specifically undistinguishable from- 

 it by external features; and, unless its internal characters should prove to be 

 different, it cannot be regarded as specifically distinct from 31. striatocostata. 

 In Iowa and Nebraska, it is confined to strata of ' the Upper Coal-Measures. 



Length of one of the specimens figured, twenty -five millimeters ; 

 breadth, twenty-six millimeters ; height, twenty millimeters ; but examples 

 are occasionally found having nearly or quite double these dimensions, but 

 in such large ones the height is not often proportionally so great. 



Position and locality. — Strata of the Carboniferous period: — Camp Cot- 

 tonwood, Lincoln County, Nevada: Tenney's Ranch, Kaibab Plateau, 

 Arizona : Kanab Canon ; Meadow Creek, south of Fillmore ; Le Verkin's 

 Creek ; and at a cliff east of Belleview, Utah. 



Family KHYNCHONELLIDJ]]. 



Genus RHYNCnONELLA Fischer, 1809. 



Rhynchonella Uta Marcou, sp. 



Plate IX, fig. 2 a, l>, and c. 



Terebratula Uta Marcou, 1858,* Geology of North America, 51. 



Rhynchonella {Camaropliora I Osagensis Swallow, 1858, Trans. St. Louis Acad. Sci., i, 219. 



Camarophora globuUna Geiuitz, 1866, Carbonformat. and Djas in Nebraska, 38 (not 



C. globuUiia Phillips, sp., 1834). 

 Rhynchonella Osagensis Meek, 1872, U. S. Geol. Surv. Nebraska, 179. 



Shell rather small, varying considerably in form, usuall}^ somewhat 

 trihedral, and a little wider than long ; postero-lateral margins converging 

 at an angle, varying in different shells from eighty to one hundred and ten 

 degrees ; front broadly rounded, emarginate at the middle. 



Dorsal valve more capacious than the ventral, abruptly convex at the 

 front ; beak strongly incurved ; mesial fold not prominent, and perceptible 

 only at the front ; plications somewhat angular, from nine to twelve in num- 

 ber, becoming obsolete at the middle and sides of the valve ; three or four 

 of these plications are borne upon the mesial fold, and there are also three 

 or four upon each side of it. 



* See foot-note concerning ilate of publication on page 125. 



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