284 PALEONTOLOGY. 



FOSSILS OF THE JURASSIC PERIOD. 



BRACHIOPODA. 



Genus RHYNCHONELLA Fischer. 



KHYNCHONELLA MYEINA 11. sp. 

 Plate VII, figs. 1-5. 



Shell of medium size, very broadly ovate, being wider than long; the 

 greatest diameter below the middle, valves depressed-convex, the dorsal 

 much the deepest and nearly evenly convex from beak to base, and also 

 transversely. Ventral valve somewhat unevenly convex, slightly flattened 

 toward the sides, and moderately depressed in front to form the proportion- 

 ally broad mesial extension ; beak rather large, pointed, strongly curved 

 upward, and projecting considerably beyond the dorsal valve. 



Surface marked by from thirty-two to thirty-four low, rounded plica- 

 tions, eight to ten of which are elevated on the doi'sal valve forward of the 

 middle of the shell, forming the rather wide but only moderately elevated 

 mesial fold and a corresponding number impressed on the ventral valve. 

 Minute surface-structure of the shell finely but evenly marked with con- 

 centric lines of growth. 



This is a very pretty species, and is characterized by the moderately 

 fine plications of the surface, which are of nearly equal strength on all 

 parts of the shell, those of the mesial elevation being hardly perceptibly 

 larger than those on the sides. The species bears considerable resemblance 

 to RliyncJionella varians Schl. of the Inferior Oolite from Whitby, England, 

 but differs in the more evenly convex valves and in the rounded plications, 

 those of that species being slightly angular in the specimens examined. 



Formation and locality. — In light-colored limestones of Jurassic age, at 

 Flaming Gorge, Uinta Range, Utah. 



RHYNCHONELLA GNATHOPHORA T. 

 Plate VII, fij;. 6. 

 Rhynchonella gnathophora Meek?, Geol. Siirv. Cal., PaL, vol. 1, p. 39, pi. 8, fig. 1. 



A few individuals referred with doubt to this species occur in the 

 collections from Flaming Gorge. The reference, however, is very unsatis- 



