1900.] HAY—VERTEBRATES OF CARBONIFEROUS AGE. LL5 
figure represents this. At the anterior end of this scale the bor- 
der just referred to is crossed by numerous fine longitudinal striz, 
or radii. At the posterior end of the scale are seen wider folds. 
These probably have something to do with the large radiating fur- 
rows which would be found on the other side. 
With the few specimens on hand it is difficult to specify charac- 
ters by means of which this species may be distinguished from 
S. hardingt. Were they both found in the same formation I would 
hesitate to separate them, but it is unlikely that: the same species 
occurs in the Subcarboniferous and in the Coal-measures. Were 
the outer surfaces of the scales exposed we might possibly discover 
differential characters. So far as the specimens of the two species 
indicate, the boss of S. Aardingi is placed nearer the centre of the 
scale than is that of S. dazwsonz.. I find on the surface of the latter 
species no such fibrillation as is seen on S. harding?, but this may be 
due to the character of the preservation. S. dawsont is a much 
smaller scale than any yet reported of S. hardingz, but we must not 
place too much reliance on this fact. 
CC@:LACANTHUS ROBUSTUS Newb. 
Celacanthus robustus, Newberry, J. S., Proc. Acad. Nat. Sci. 
Fhila., Vili, 1856; p. 98; Geol. Surv. Ohio; Pal. 1, Pt. “2, 
1873, p- 341, Pl. xl, Figs. 2, 2a; Pal. Kishes N. America; 
1890, p. 228; Huxley, T. H., Mem. Geolog. Survey United 
Kingdom, x, 1866, p. 14; Woodward, A. S., Cat. Foss. 
Fishes, Pt. il, 1891, p. 406. 
Rhabdoderma robustum, Reis, O. M., Paleontographica, xxxv, 
1888, p. 71. 
A single scale of this species has the U.S. Natural Museum’s 
Catalogue No. 4336. It also bears Prof. Cope’s number F, 37, 
and belongs to the Lacoe collection. Prof. Cope has labeled it 
“¢ Celacanthus sp. Cope, Mazon creek, Illinois.’’ It seems to me 
that it certainly belongs to C. robustus Newb. ‘The species was 
originally described from specimens found in the coal measures at 
Linton, O. So far as Ican judge, from a comparison of the Mazon 
creek specimen with the description and figure presented by New- 
berry, there is no important difference, unless it is that of size and 
proportions. ‘The Mazon creek scale has a length of 23 mm. and 
an extreme width of 14 mm. Dr. Newberry’s specimen figured 
had a length of 20 mm. and a width of 14 mm., being therefore 
