44 THE ROYAL SOCIETY OF CANADA 
scales near the dorsal and ventral midline. The scales of the midline 
of the back are not preserved in the specimen. 
The sculpture of the scales, which gives them a decidedly 
rough or rugose appearance, consists of from about five to seven 
broadly rounded ridges running obliquely backward and downward 
on the scale with a general appearance, accentuated in some of the 
scales, of convergence toward the postero-inferior angle of the scale. 
The ridges bend upward anteriorly and downward posteriorly (figures 
2 and 3). They are not of equal breadth and often the larger ridges 
are divided longitudinally by a shallow groove for the whole or, more 
frequently, part of their length so as to assume the appearance of 
bifurcating forward or backward according as to whether the ridge 
is shallowly grooved anteriorly or posteriorly. On the ridges are 
also observed at intervals along their length a number of inconspicuous 
nodes or transverse swellings which help to accentuate the roughness 
of the scale sculpture. The ridges end posteriorly as denticulations 
of the scale margin. 
The few scattered scales, already mentioned as preserved in the 
rock just outside the limits of the trunk, display the smooth inner 
surface with a well defined socket in the lower half at the midlength | 
of the scale and a peg arising from the middle of the upper margin, 
figure 4. In these scales, which appear to be anterior flank ones, the 
entire outline is visible, showing that the front edge is straight and that 
the upper front angle is produced upward to about half the height 
of the peg. The denticulations along the posterior margin are conspic- 
uous and antero-inferiorly the edge is broadly rounded. 
All the drawings illustrating the above descriptions, and repro- 
duced in the accompanying plates, have been made by Mr. Arthur 
Miles. 
