EASTMAN : CARBONIFEROUS FISHES FROM THE CENTRAL WEST. 189 



surface slightly concave, with at least seven prominent, rather broad and 

 coarsely tuberculated ridges, the tubercles gradually decreasing in size from 

 the abrupt outer towards the narrow inner margin. 



This species is represented by a unitiue upper dental plate belonging to the 

 Yale Museum, which is readily distinguished from other species by its abbre- 

 viate form and nearly straight parallel ridges. The tuberculations of the lat- 

 ter are coarser and less acuminate than in S. vabasensis Cope,^ and the ridges 

 resemble some species of Ctenodus in their non-radiating character. A narrow 

 and elongate cranial plate, having the dimensions of 5 by 10 cm., and belong- 

 ing to the same collection, may perhaps be correlated with this species. All 

 other Dipnoan remains from the Mazon Creek locality are founded on detached 

 scales. 



Formation and Locality. — Coal Measures ; Mazon Creek, Illinois. 



CROSSOPTERYGII. 



COELACANTHIDAE. 



COELACANTHUS Agassiz. 



J. S. Newberry 2 records having received from Mazon Creek "a single spec- 

 imen each of Eurylepis and Coelacanthus, probably not distinct from those 

 found at Linton," Ohio. No examples of the former genus have come under 

 the writer's observation, but ornamented scales and head-plates referable to 

 Coelacanthus sometimes occur in Mazon Creek nodules, and very rarely there 

 are found complete fishes of small size, evidently quite distinct from those 

 occurring elsewhere. In most specimens the posterior dorsal, anal, and pectoral 

 tins are wanting, and one might be led to suppose at first that the second dorsal 

 had become lost through specialization. A .single example preserved in the 

 Museum of Comparative Zoology shows it very distinctly, however, and the 

 absence of this and the anal fin in other examples is therefore attributable to 

 faulty preservation. 



Coelacanthus exiguus Eastman. 



(Plate 5, Fig. 48.) 



1902. Coelacanthus exiguus C. R. Eastman, Journ. Geol. Vol. X., p. 538, Text-fig. 3. 



Type. — Complete individual; Yale Museum. 



A small species, attaining a maximum length of about 4.5 cm. Trunk nar- 

 row and elongated, the head occupying about one- fourth of the total length. 

 First dorsal consisting of relatively few stout rays, and situated slightly in 



1 Journ. Geol. Vol. VIII., 1900, p. 704, Pi. 1, Fig. 7. 



2 Men. U. S. Geol. Surv., Vol. XVI., 1«89, p. 215. 



