274 PROCEEDINGS OF THE NATIONAL MUSEUM. 



RHADINICHTHYS GRACILIS (Newberry and Worthen). 



Plate 9, fig. 4. 



Palaeoniseus gracilis Newberry and Worthen, Pal. Illinois, vol. 4, 1870, p. 347, 

 pi. 3, fig." 4. 



The original illustration of this species, the only one hitherto pub- 

 lished, is unsatisfactory in several respects, and the description given 

 is very meager. The distinguishing characters are stated to consist 

 in the smooth rhomboidal scales and remote position of the dorsal 

 and anal fins, which are directly opposed to each other. The illus- 

 tration which appears in the accompanying plate 9 is reproduced 

 from a photograph of a well-preserved small specimen from the Mazon 

 Creek locahty (catalogued as No. 4401). The dorsal, of compara- 

 tively fev/ rays, is very remote, and may have been displaced back- 

 ward by deforming agencies during the fossilization process. The 

 anal comprises 7, and the ventrals 6, well-separated rays. The head 

 parts are not distinctly sho^^^l, and the squamation in the anterior 

 part of the trunk has been disturbed. This would seem to be a very 

 rare foi-m in the American Carboniferous. The holotype is preserved 

 in the Peabody Museum of Yale University. 



Formation and locality. — Coal Measures; Mazon Creek, Grundy 

 County, Illinois. 



Genus ELONICHTHYS Giebel. 



An amended diagnosis of this genus has been published by Tra- 

 quair in his Monograph on the Ganoid Fishes of the British Carbonif- 

 erous Formations (1877, p. 47). Four species have been described 

 from the Pemisylvanian of the Mazon Creek locahty, one of which, 

 E. peltigerus Newberry, occurs also at Linton, Ohio. It is not known 

 where the holotype of the latter species is preserved, but the counter- 

 impression of the closely allied E. hypsilepis Hay is now the property 

 of the United States National Museum (Cat. No. 4848) . 



ELONICHTHYS HYPSILEPIS Hay. 



^ Plate 9, fig. 3; plate 10, fig. 3. 



Elonichthys peltigerm hypsilepis Hay, Proc. Amer. Philos. See, vol. 39, 1900, 

 p. 117, pi. 7. 

 The material at Doctor Hay's command at the time of establish- 

 ing this species (regarded by him as doubtfully distinct from E. jielti- 

 gerus) consisted of seven specimens, the most perfect one of which 

 was figured by the author in an excellent photographic reproduction. 

 As contrasted with E. peltigerus, Hay noted that in all of the speci- 

 mens examined by him which were well enough preserved, "the 

 scales in several perpendicular rows just behind the shoulder girdle 



