338 



THE CANADIAN NATURALIST. 



[Vol. 



Vlll. 



corresponding to the teeth of the edge. The ridges are arranged 

 in an upper and lower series, the latter oblique to the former, so 

 that each scale has the appearance of being composed of two 

 distinct portions. Lower surface of scales smooth, with a few 

 furrows corresponding to the ridges above, and the posterior 

 edges similarly serrate. Caudal scales narrowly rhombic, 

 pointed, and with a few central lines. The back is protected 

 with about ten large oval scales between the head and the dorsal. 

 They are sculptured with waving lines, curving with the edges, 

 and are apparently truncate and serrate behind. The fish figured 

 by Jackson, PI. II, Fig. 5, but not named, probably belongs to 

 the above species. 



ft 



Fig. Palxoniscus Modulus, N. S. 



(a) Outline, natural size. 



(6) Series of Scales enlarged, seen from inside. The lower row are 

 those on mesial line. 



(c) Surface of exposed part of scale from side and upper lobe of 



tail, showing sculpture, enlarged. 



(d) One of the dorsal scales, enlarged. 



This beautiful and elaborately ornamented little fish is a per- 

 fect model in miniature of that type of lower carboniferous 

 Palseoniscids to which it belongs, and which has recently been 

 separated by Dr. Traquair in the genus or subgenus Rhadin- 

 ichthys. For this reason, I have given it the specific name 

 modulus. To the same genus belong the two next species, 

 described by Jackson, of which I shall give merely distinctive 

 marks. 



P. Alberti, Jackson, is larger than the preceding. The scales 

 have more numerous striae. The dorsal scales are rounded pos- 



