246 PROCEEDINGS OF THE NATIONAL MUSEUM. 



DeTonian) of Ohio." Some half-dozen species, all of them founded 

 on isolated teeth, are known from tlie Chemimg-Catskill of New York 

 and Pennsylvania, and great numbers are found in the Middle and 

 Upper Devonian of Iowa. Although fish remains were reported from 

 the Ouray limestone in the San Juan region of Colorado as long 

 ago as 1874, and several species were brought to light by Dr. Wliit- 

 man Cross in 1904, from the immediately underlying Elbert forma- 

 tion in the same region, no Dipterine remains were collected from 

 the Colorado Devonian until the year 1909, when detached dental 

 plates referable to three species already known from the Iowa Devo- 

 nian were obtained by Doctor Cross. These specimens are now pre- 

 served in the Museum collection, and may be identified as belonging 

 to Dipterus mordax, D. pectirmtus, and D. digitatus. A single smooth 

 crushing plate suggestive of the Synthetodus type of dentition is also 

 contained in the collection made at the new locahty, which is in the 

 Elbert formation of Florida Valley, east side, in the Ignacio Quadrangle 

 of southwestern Colorado. 



A more particular account of these remains has recently been 

 published (1915) in the Annals of the Carnegie Museum.^ It may be 

 here stated, without entering into details, that the evidence fur- 

 furnished by the three above-named species of Dipterus, and one un- 

 described Syntlietodus-'hke plate, is sufficient for establishing a close 

 correlation between the Elbert formation of Colorado and the Upper 

 Devonian of the Cedar Valley region of Iowa. According to this cor- 

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

 stone than has hitherto been conceded.^ The recent discovery of 

 Dipterine remains in the San Juan country also simpUfies the problem 

 of distribution of this class of fishes in the Devonian. For we now 

 find evidence that the line of communication between the Appala- 

 chian and Cordilleran regions during late Devonian times was actually 

 by way of theOliioan and Dakotan seas; and also that intermigration 

 took place between the faunas of the Elbert formation and the so- 

 called State Quarry beds of Iowa toward the close of the Devonian. 

 This statement finds further confirmation in a discovery made by 

 Dr. E. Kirk during the past year (1914) of a well-preserved Dipterus 

 dental plate from the type section of the Jefferson limestone on Gal- 

 latin River, near Logan, Montana. The specimen has been recently 

 added to the Museum collection. In plate 7, fig. 6, is shown a Coccos- 

 tean ventro-lateral plate from the Elbert formation of the San Juan 

 region, collected by Doctor Cross. Although clearly of arthrodiran 



1 Staufler, C. S. The Middle Devonian of Oliio. Bull. Geol. Surv. Ohio, 1909, No. 10, p. 196. 



2 Eastman, C. R. Dipterus remains from the Upper Devonian of Colorado. Annals Carnegie Mus., 

 vol. 9, 1915, No. 3, pp. 27&-2S3. 



3 Hay, O. P. Description of a new species of Cladodus ( C. formosus) form the Devonian of Colorado. 

 Amer. Geologist, vol. 30, 1903, pp. 373-374. Girty.G.H. Devonian fossils from Colorado. The faiuia of the 

 Ouray limestone. 20th Ann. Kept. U.S. Geol. Surv., 1900, pt. 2, pp. 25-81. The Devonian fauna of the 

 Ouray limestones. Bull. U. S. Geol. Surv., 1909, No. 391, 36 p., 10 pis. 



