660 E. B. BRANSON 



and Lower Coal Measures in the Mississippi Valley, and occurs in 

 the Marshall of Michigan. 



Better ophon belliis Keyes (PI. Ill, Figs. 16 and 17) 

 1895. Bellerophon belliis Keyes, Mo. Geol. Surv., V (1894), 148, PI. 50, Fig. 7. 



Found in the Upper Coal Measures, Kansas City, Missouri. 

 1S99. Patellostium nodocostatum Girty (not Gurley), igth Ann. Rept., U.S. 



Geol. Surv., Part 3, p. 590. Found in the Upper Coal Measures, Atoka 



quadrangle. 

 1903. Patellostium helium Girty, U.S. Geol. Surv., Prof. Paper 16, pp. 474-75. 



Found in the Hermosa and Rico formation, San Juan region, Colorado. 

 1906. Bellerophon bellus Woodruff , Geol. Surv. Nebr., Vol. II, Part 2, p. 282, 



PI. 15, Fig. 2. Extreme upper part of the Coal Measures of Nebraska. 



Only one specimen of this species was found, and it agrees 

 in every detail with Keyes's description, though the transverse 

 ridges are not as regular as shown in his figures. The following is 

 the original description: 



Shell subglobose, expanding rapidly at the aperture, which is somewhat 

 reniform, with the lip reflected at the sides. Surface marked by a rather 

 prominent, longitudinal carina along the median portion of the shell; strong 

 transverse ridges parallel to the lines of growth pass from one umbilical region 

 to the other; these are crossed by less prominent longitudinal lines, the two 

 sets forming a beautiful cancellated area. 



The Embar specimen was collected in the Big Popo Agie Canyon, 

 S.W. iS. 16, T. 32 N., R. 100 W. 



CONCLUSIONS 



i. The abundance of cochliodont sharks, which have never 

 been reported from strata younger than the Pennsylvanian, indicate 

 an age older than the Permian. 



2. The presence of invertebrates that are nearly all referable 

 to species occurring in the Upper Coal Measures of the interior 

 and of sharks that are also common to the Upper Coal Measures 

 indicate the homotaxy of the Lower Embar of Wyoming and the 

 Upper Coal Measures of the Mississippi Valley. 



3. The presence of a peculiar genus of shark in the Moscowian 

 of Samara, Russia, and in the Embar makes probable the correla- 

 tion of these widely separated formations. This conclusion is 

 strengthened by the presence of Chomalodus corrugatus in the Rus- 



