1900.] HAY—VERTEBRATES OF CARBONIFEROUS AGE; lls 
STREPSODUS ARENOSUS sp. nov. 
There has been placed in my hands by Dr. David White, of the 
United States Geological Survey, for identification, the imprint of 
the external surface of a scale of a species of the 
genus Strepsodus. This fossil was collected by 
Dr. White from a shale near the base of the 
Lower Carboniferous rocks, in the vicinity of 
Collier’s Station, Blair county, Pa. 
The scale is somewhat imperfect, through the 
loss of a small portion of the distal, or free bor- 
der. Nevertheless, enough is present to give us all 
the essential characters. The scale has had a_ Fic. 3. Strepsodus 
length of about 28 mm. and a breadth of 21 mm. Satay 
The proximal, or attached, end has been broadly rounded ; the free 
end was also rounded, but probably less broadly. The most con- 
spicuous feature of the ornamentation of the fossil is found in the 
system of furrows, which resemble a tree with its trunk and branches. 
These furrows, according to Mr. A. S. Woodward, are on the ex- 
ternal surface of the scale. ‘The main trunk is a furrow which began 
a little proximad of the centre of growth and a little less than one- 
third the length of the scale from its attached end. This, or a por- 
tion of it, would be represented on the other side of the scale by 
an elevation, or boss. At about the centre of the scale the main 
furrow begins to give off lateral branches in such a way that, like 
a deliquescent tree, it is soon lost. The smaller divisions of the 
branches were carried out to the free border of the scale. 
The surface of the scale is everywhere covered by a fine, almost 
microscopic sculpture, which is produced by numerous elevated 
points. ‘These are arranged in either concentric or radiating lines 
and often in both. There are about ten of these lines in a milli- 
metre. On the upper and lower sides of the scale the concentric 
lines predominate ; on the posterior portion of the scale the radiat- 
ing lines are more conspicuous. These lines of minute elevations are 
also found in the furrows. Near the free border of the scale the 
elevations appear to have coalesced in rows, so as to make contin- 
uous longitudinal ridges. 
The specific name has been suggested by the sculpture of the sur- 
face, which resembles grains of fine sand arranged closely together 
in rows. 
PROC. AMER. PHILOS. 80C. xxxIxX. 161. H. PRINTED APRIL 17, 1900. 
