282 Annals of the Carnegie Museum. 



of the Elbert formation. Briefly, the new data consist in tlie dis- 

 covery of a small number of extremely characteristic Dipnoan re- 

 mains — Dipterine and Synthetodont teeth — which have been here- 

 tofore known from but a single horizon and locality, namely the 

 Upper Devonian State Quarry beds of Johnson County, Iowa. Illus- 

 trations are given in the accompanying text-figure of several of these 

 teeth, all of which were obtained by Dr. Cross in July, 1909, from the 

 Elbert formation of Florida Valley, east side, in the Ignacio Quad- 

 rangle of southwestern Colorado. The originals of these figures are 

 preserved in the United States National Museum. 



The specific identity of the Dipterus remains admits of not the least 

 particle of doubt, the following forms being easily recognizable: D. 

 mordax, D. pectinatus, and D. digitatus. The Synthetodont type of 

 crushing plate (Fig. i) is probably new, but is left unnamed for the 

 present, or until such time as further material is available for pre- 

 paring a satisfactory diagnosis. One cannot be altogether certain 

 in the case of the unique specimen shown in the figure w'hether we 

 have to do with a single complete dental plate, or with one of the 

 halves of a composite pavement, such as we are familiar with in the 

 type species of Synthetodus. 



Without entering into details it may be stated that the evidence 

 afforded by the three above-named Dipterine species, and one unde- 

 scribed Synthetodns-Wke type of dental plate, is sufficient for estab- 

 lishing a close correlation between the Elbert formation of Colorado 

 and the Upper Devonian of the Cedar V^alley region of Iowa. In 

 addition, the occurrence of Diptcnis scales in the fish-bearing beds at 

 Aspen confirms the belief in a synchronism between those beds and 

 the Elbert formation in the San Juan country. According to this 

 correlation a somewhat later age must be assigned to the Ouray lime- 

 stone than that which Drs. Hay and Girty have been willing to 

 concede for it.' 



That which in 1904 appeared difficult of comprehension was how 

 certain characteristic species from the Chemung-Catskill of the 

 Appalachian region should have transmigrated into the Cordilleran 

 sea by way of the Dakotan, without admixture being found in the 

 Colorado Devonian of western Upper Devonian forms of fish life; 

 and it was suggested at that time that the Chemung-Catskill of the 

 Colorado Devonian fauna must ha\'e come by another route than by 

 the Dakota sea. 



Amer. GeoL, Vol. XXX, 1903, p. 373. 



