STANTON.] 



OSTREIDiE. 57 



deep longitudinal farrow; surface apparently only with moderately 

 distinct marks of growth. Upper valve almost nearly flat externally, 

 but nearly as concave as the other within; beak usually a little trun- 

 cated; ligament area marked with strong transverse striae, and having 

 its mesial ridge very prominent, and occupying as much as one-third 

 its breadth; surface as in the other valve, or perhaps a little smoother. 



"Length of adult examples about 18 inches; breadth of same about 

 2-50 to 3 inches. 



il Although not a very uncommon species, I have seen no entire speci- 

 mens of this remarkable shell. It will be readily known by its usually 

 narrow, elongated, and generally straight form. The shell is usually 

 found broken into several pieces, but casts of the internal cavity are 

 not unfrequently met with entire. One of these before me is nearly 1 

 foot in length and only 2 inches in breadth. It often had a curious habit 

 of growing in groups of three shells, attached to each other by the 

 backs of their beaks. I have seen large numbers of them closely 

 arranged, or nearly in contact with each other, at Coalville, all with 

 their beaks downward, or at right angles to the planes of the sandstone 

 strata. When found where it grows isolated, the shell is sometimes 

 arched to one side. 



u Locality and position. — This species ranges through nearly the whole 

 thickness of the Cretaceous sandstones near Coalville, Utah, and is 

 also found in the Cretaceous coal-bearing sandstones at Bear River city, 

 Wyoming, as well as in a sandstone ridge of same age on Union Pacific 

 railroad, a few miles east of the latter locality." 



The above is Prof. Meek's revised description of this species, which, 

 as he intimates, ranges from beds containing an undoubted Colorado 

 fauna far up into those that probably belong to the Montana. 



Associated with the very slender forms there are other shorter ones 

 broadly ovate in outline that apparently belong to the same species. 

 The specimens from southern Utah that were referred to Ostrea cortex 

 are of this character. The beaks are usually more or less exogyrate in 

 form, this feature being most marked on the upper valve of the broader 

 specimens. The same species occurs in the Lower Cross Timber sands 

 stone of Denton county, Tex. 



OSTEEA MALACHITENS1S n. Sp. 



PI. II, Figs. 5, 6, 7, and 8. 



Shell rather small, irregularly subtriangular in outline; cardinal 

 margin long and nearly straight, more or less distinctly auriculate in 

 front cf the beaks, which are small and inconspicuous; lower valve 

 moderately convex, with the greatest convexity along an oblique line 

 from the beak to the middle of the postero-basal margin, which is there 

 broadly emargiuate, thus giving the shell a saddle-shaped or bilobate 

 form. The outline of the shell, exclusive of this broad lobe and the 



