1900.] HAY—-VERTEBRATES OF CARBONIFEROUS AGE. 101 
from those on the body. I am convinced that we must rely more 
on the arrangement of the system of nutrient canals found in these 
scales, and on the sculpture of the surface. The availability of 
both these characters depends somewhat on the perfection of 
preservation of the scale, but usually they can be satisfactorily 
determined. 
To the writer it seems highly probable that the fishes of this 
genus, like their existing relatives, lived in fresh waters, probably 
in rivers which emptied into the sea in which the Mazon creek 
deposits were formed. 
In such cases, when the fishes died, their bones would be left in 
the bottom of the rivers where they had lived, while numbers of 
their scales would be likely to be carried to the sea. This may 
account for the fact that no portions of the bony skeletons of any 
of the species has yet been found in the regions of Mazon creek. 
If it appears remarkable that even seven species of the genus 
should be found entombed in one locality, we may suppose that 
possibly these inhabited as many branches of some great river and 
therefore were, when living, denizens of widely separated regions. 
It may further be said that it is not wholly certain that the 
species described here as members of Sagenodus really belong to 
that genus. So far as regards ornamentation, none of the scales 
here called Sagenodus much resemble the figure of the scale of 
the type of the genus (.S. e/egans) given by Hancock and Atthey.? 
However, Fritsch? has presented much better figures of the same 
species, and these appear to possess the generic characters of our 
specimens. 
SAGENODUS OCCIDENTALIS (Newb. & Worth.). 
Rhizodus occidentalis, Newberry and Worthen, Geol. Surv. Lllinots, 
ii, 1866, p. 19, Fig. 2; Geol. Surv. Llinois, iv, 1870, Pl. iv, 
Fig. 1; Newberry, J. S., Pad. Fishes NV. Amer., 1890, p. 192 3 
Miller, S. A., V. Amer. Geol. and Pal., 1889, p. 611, Fig. 
1173 5. Woodward, A.>S., Cat. Loss. Fishes, Pt. 1, 189%, p. 
348 (referred with doubt to Strepsodus). 
Sagenodus occidentalis, Cope, E. D., Proc. AMER. PHILOS. Soc., 
Xxxvi, 1897, p. 75, in part; Williston, S. W., Kansas Univ. 
Quart., vili., 1899, p. 177. 
1 Ann. Mag. Nat, Hist. (4) vii, 1871, Pl. xiii, Fig. 3. 
2 Fauna der Gaskohle, ii, 1888, Pl. 1xxx. 
