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ART. XXVI. — Descrij)tioHS of New Fossil Shells of the (Jnited Stales. 



By T. A. CoxRAD. 



GNATHODON, Graij. 



Gnathodon Lecontei. pi. 24, fig. 1, 2. — Obliquely ovato-triangular, veutiicoscj anterior side short, the 

 margin regularly rounded; posterior side cuneiform; umbonal slope oblique, carinated; carina not 

 prominent, obtuse, except on the umbo, where it is rather acute ; right valve with two cardinal teeth 

 separated by a profound pit; left valve with one cardinal bifid tooth nearly direct; lateral teeth promi- 

 nent and acute; posterior one elongated, slightly curved; anterior one about half the length of the." 

 posterior tooth, slightly curved. 



Localitij. Southern District of Upper California. Dr. Le Coiite, 



This interesting species approaches the recent G. cuneatum nearer than the fossil 

 G. Grayi. It is much smaller than those, and the carinated umbonal slope is a 

 character which prominently distinguishes it from either. 



No recent species of Gnathodon is known to occur in California, and this fossil 

 may be of the Miocene period. If it is still existing, it will probably be found where 

 the fresh water of the Gila mingles with the salt water of the Gulf of California. 



Dr. Le Conte, to whom I have dedicated this inteiesting shell, found it north of 

 Carisco creek, in limestone beds formed almost entirely of the species, and further in 

 the desert it occurred in clay, lying almost horizontally. This is at a distance of 

 120 miles from the Gulf of California, and 150 miles from the Pacific. 



Cretaceous Species. 

 EXOGYRA, Say. 



ExoGYRA CAPRINA. PI. 24, fig. 3, 4. — Vcutricose ; larger valve having the umbo spiral, or shaped like a 

 ram's horn ; back with obtuse or obsolete angles and furrows, and undulated strong lines of growth ; 

 superior valve convex. 



Locality. San Felipe creek, near Rio Grande, western Texas. Dr. Woodhoiise. ■ 



A single specimen of this curious species was obtained by Mr. Edward H. Kern, 



in New Mexico, and Dr. W. found it abundantly in Texas. The strata in which they 



occur are probably synchronous with those of New Jersey. Dr. W, found, also, 



Exogijra Boussingualtii, D'Orbigny, and Gryphcea Pitcheri, Morton, in western 



Texas. 



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