350 EXPLOEATIONS ACROSS THE GEEAT BASItf OF UTAH. 



Prodtjctus multistriatus, Meek. 



Plate 1, fig. 8, a, b. 



Product,,* muUhtriata, Meek, (July. ISIOj. Proceed. Acad. Nat. Sci., Philad., xii, 309. 



Shell above medium size, breadth nearly double the length, from the hinge direct 

 to the anterior slope ; hinge-line longer than the breadth of the shell in front of it ; 

 ears moderately large, triangular, distinctly vaulted, and standing nearly at right 

 angles to the swell of the larger valve. Ventral valve extremely ventricose, strongly 

 arched, and provided with a broad, deep mesial sinus, extending from the beak to the 

 front; beak rather small, compressed, and projecting little beyond the hinge. Dorsal 

 valve deeply concave, provided with three broad, obscure radiating prominences, one 

 of which corresponds to the mesial sinus of the other valve, and the other two radiate 

 to the lateral margins in front of the ears. Surface of both valves marked by numer- 

 ous very fine, obscure, radiating strise, and destitute of spines, excepting about three 

 near the extremity of each ear, and a few on the anterior slope of the ventral valve. 



Length of hinge, near 1.77 inches; length from hinge to anterior slope, 1 inch; 

 greatest breadth in front of the hinge, 1.48 inches. 



None of the specimens show concentric lines or wrinkles, but as they are all a 

 little worn, there may have been very fine marks of growth. The radiating strise are 

 small, very regular, and number about ten to twelve in the space of 0.20 inch ; they 

 appear to increase chiefly by intercalation. The swell of the arched portion of ventral 

 valve is very prominent, and has, in consequence of the deep mesial sinus, a more or less 

 distinct bilobate appearance ; while the lateral slopes are very abrupt, and its anterior 

 and lateral margins considerably produced. Judging from the few remaining bases of 

 spines on the ventral valve, they seem to have been strong and erect. 



Locality and position.— Yellowish limestone series, east side of Long Valley, lati- 

 tude 39° 57' north, longitude 115° 10' west, where it is quite common; probably Upper 

 Carboniferous. 



Genus ATHYRIS, McCoy. 

 Athyris subtilita, Hall (sp.). 



1 ■ • *'"• 4 > «. &•— Meek (1872), Paleont. E. Nebraska 



There are several characteristic specimens of this well-known shell in the collec- 

 tions from the Coal-Measures of Eastern Kansas, and quite a number of apparently 

 the same species from the Yellow Limestone series so extensively developed 



oftl 



hit Mountains. The specimen 



figured, winch is rather smaller than the average size of its associates, is from the latter 

 locality. Some of the larger specimens are more compressed, and have a more distinct 

 mesial sinus than the one figured. None of those from this distant western locality are 



