1900.] HAY—VERTEBRATES OF CARBONIFEROUS AGE, 105 
radiate from the centre of growth, and the observance of which 
require the use of a lens. The fields (c) and (@) are occupied by a 
very few nutrient canals which form a few large cells. The most 
conspicuous of these canals run from the centre of growth to the 
upper and lower borders. It is in these two fields that the system 
of concentric lines is most strongly developed. Another scale (U. 
S. Nat. Mus., No. 4429) does not display nearly so well the system 
of nutrient canals, but the remainder of the ornamentation is well 
shown. A third quadrate scale from the Lacoe collection (U. S. 
Nat. Mus. Cat., No. 4426) is the largest I have seen, having a 
length of 94 mm. and a breadth of 62 mm. It has the characters. 
of the species well displayed. j 
In the portion of the Daniels’ collection in my hands for descrip- 
tion is another scale (Daniels’ No. 8) which is of oval form, 45 mm. 
long by about 29 mm. wide. The ornamentation, including the 
network of canals of this scale, is identical with that of the scale I 
have above described as S. guadratus. No character except form 
will separate the two. Another scale ( Daniels’ No. 19) has a length 
of 68 mm., a width of 48 mm., and an oval form. I cannot 
hesitate to place both of these in S. guadratus. 
In Prof. Cope’s paper already cited, on p. 77, he refers certain 
scales belonging to the Lacoe collection to S. occidentalis, and 
among them one whose two impressions are labeled F. 1, F. 
2.1 This scale is 40 mm. wide and 50 mm. long. I find few 
characters which would permit it to be referred to S. occzdentalts, 
while most of the characters of S. guadratus are present. I have 
hesitated to place it here because the area, including the centre of 
growth, which in most specimens is occupied by a rather coarse 
areolation, is in this scale broken up into an extremely fine mesh- 
work ; but the other scales differ among themselves in this respect. 
In form, the scale is closer to the typical S. guadratus than are the 
other oval forms that I have referred to this species, being propor- 
tionally broader and having the anterior and posterior borders 
more broadly rounded. It is also, as regards form, as far removed 
from the original specimens of S. occidentalis as it is from those of 
S. guadratus. 
The scale mentioned by Prof. Cope as probably belonging to S. 
1In the paper referred to, these scales are designated by the symbols “ Figs. I- 
2, I9-20, 99.” This is probably an editorial error for F, 1, 2; 19, 20; 99, which 
symbols we find on the specimens, 
