1900.] HAY—VERTEBRATES OF CARBONIFEROUS AGE. 111 
sculpture of the scale resembles closely that of Rhizodopsts robus- 
tus, as shown by Figure 3 of Plate xvi of Mr. A. Smith Woodward’s 
Catalogue of Fossil Fishes, Partii; and I place the species in that 
genus provisionally. The only reason I have for doubting the cor- 
rectness of this assignment is the existence of a network of anas- 
tomosing lines throughout the denser portion of the scale, or some- 
thing more than the proximal one-half of the area of the scale. 
This network is exceedingly irregular, like the cracks in dried 
mud, but nevertheless reminds much of the network of nutrient 
canals found in the scales of Sagenodus. In the scale before me 
these apparent canals are occupied by the white mineral which is 
so often found in fossils from this locality. It is not improbable 
that the bony substance of the scale has shrunken and cracked and 
the cracks been filled up with a foreign substance. If it shall 
prove that these are really nutrient canals the scale will represent 
apparently an undescribed genus close to Sagenodus. 
The scale here described is ovate in form, being somewhat 
pointed at the proximal end. Its length is 25 mm, its breadth 
14.3mm. The proximal half has been osseous and rather thick, 
its thickness now, after the compression to which it has been sub- 
jected, being about equal to that of ordinary book paper. 
The centre of growth or nucleus is located very close to the cen- 
tral part of the scale and the sculpture is disposed with reference 
to this nucleus. Concentric lines of growth appear on the lower 
surface of the osseous substance and on the underlying matrix. 
From the nucleus thread-like lines radiate to the proximal border 
of the scale and cover a broadly wedge-shaped area. Of these lines 
there are about ten in a millimetre. Similar lines, starting from 
the free border of the scale, converge toward the nucleus, but the 
outer ones, upper and lower respectively, pass above and below the 
nucleus and assume the position of concentric lines. 
STREPSODUS HARDINGI (Dawson). 
Rhizodus hardingt, Dawson, J. W., Acadian Geology, 1868 and 
1878, p. 255, Fig. 77, a—d. 
Strepsodus hardingi, Woodward, A. S., Cat. Fossil Fishes, ii, 1891, 
Pp. 353- 
This is the only North American species which has up to this 
time been assigned to this genus. It was named and figured by 
