642 E. B. BRANSON 



The phosphate exposures are in vertical cliffs and could not 

 be better. Nos. 20 to 29 probably represent the upper phosphate 

 bed in the Big Popo Agie Canyon region. The rocks above the 

 lowest phosphate horizon contain few fossils and cannot be corre- 

 lated by means of them. 



The rock in which the fish remains occur is a sort of coquina, 

 made up, for the most part, of pedicle valves of Orbiculoidea 

 utahensis (I have seen only one brachial valve) . Remains of many 

 small pelecypods and gastropods are common. Just below the 

 phosphate there is a silicified coquina made up almost entirely of 

 pelecypod shells so closely packed that it is almost impossible to 

 get out a good one. 



The fish fauna contain six species that also occur in the Upper 

 Coal Measures of the Mississippi Valley and one species that is 

 known only from the Middle Carboniferous (Moscowian) of Samara, 

 Russia. Stuckenberg 1 figures it as " genus et sp. indeter.," but 

 gives no description, and the writer had described it as a new genus 

 before seeing his paper. The genus is so widely different from any 

 other that its presence in the two regions is significant for correla- 

 tion purposes. One species, Cladodus occidentalism occurs in the 

 Embar, the Upper Coal Measures of the Mississippi Valley, and 

 the Moscowian. 



The invertebrates in the fauna are mainly gastropods and 

 pelecypods and are poorly preserved. Most of the identifications 

 are uncertain, but nearly all the specimens may be referred to 

 species that occur in the Coal Measures of the Mississippi Valley. 



DESCRIPTIONS OF SPECIES OF EMBAR FISHES 

 Helodus subpolitus n. sp. (PL I, Figs. 6-16) 



The teeth of this species resemble those of Helodus politus so 

 closely that they are not distinguishable in every case, but the 

 differences are constant enough to warrant recognition. 



The teeth are of various forms and sizes, generally oblong and with 

 rounded or quadrangular ends, and slightly arched in both direc- 



1 A. Stuckenberg, "Die Fauna der obercarbonischen Suites des Wolgadurch- 

 bruches bei Samara," Memoires du Comite Geologique, Nouvelle Serie, Livraison 23, 

 1905- 



