20 THE ROYAL SOCIETY OF CANADA 



was probably received in a socket or depression in the scale next 

 above in the vertical series. The specimen, however, is so flattened 

 by extreme pressure that much of the relief of the inner scale surface 

 is lost. The upper and front margins of the scales can be traced with 

 the aid of a lens and the vertical ridges, though flattened, are con- 

 spicuous. 



The overlapping ridge-scales of the upper lobe of the tail decrease 

 rapidly in size from the caudal pedicle backward to near the extremity 

 of the lobe. In the specimen the end of the upper caudal lobe 

 is missing but its outline is probably as indicated in the plate. These 

 scales have broken along their longitudinal mid-line, as already 

 explained, and are seen from within. They are crushed and broken 

 and their exact outline is not seen but in general shape and disposi- 

 tion they agree with corresponding scales in members of the Platy- 

 somidae and Palaeoniscidae. At about 15 mm. below the anterior 

 upper margin of the tail their lower edge forms a well defined line which 

 approaches the margin as the scales grow smaller posteriorly. In 

 this basal line, behind the caudal pedicle, there are three scales rep- 

 resented in a space of 50 mm. Posteriorly four scales apparently 

 occupy half that space. 



The body prolongation in the upper caudal lobe narrows rapidly 

 backward and ends some distance anterior to the back termination 

 of the lobe. The scales covering the body prolongation are diamond- 

 shaped with a length about four times their breadth (height). They 

 are largest beneath the ridge-scales anteriorly where there are four 

 in a space of 50 mm. In passing downward and backward on the body 

 prolongation these scales become smaller, the decrease in size being 

 especially marked in the hinder ones. 



On a strip of the body surface above the long base of the anal 

 fin, the large flank-scales are replaced by comparatively small oval 

 scales with their longer diameter fore and aft. The area covered by 

 these small sized scales is about 70 mm. broad at the lower body angula- 

 tion, and it narrows gradually backward to the caudal pedicle, the 

 size of the scales also diminishing. In front of the mid-length of this 

 area there are two scales in a space of about 24 mm. measuring from 

 front to back. 



On approaching the dorsal margin of the body beneath the base 

 of the dorsal fin the flank-scales diminish in size; they become narrower 

 in proportion to their length and retain a well-developed anterior 

 inner keel. Toward the ventral margin anterior to the anal fin, and 

 near the dorsal margin in front of the dorsal fin a diminution in the 

 size of these scales is not so apparent. 



