32 THE CANADIAN NATURALIST. [Vol. X. 



mentation of its scales, and in the fact that the fin rays of its 

 second dorsal and anal fins are both supported by three osselets 

 articulated to a broad interspinous apophysis, this genus some- 

 what cloBcly resembles the Tristichopterus of Sir Philip Egerton. 

 But the vertebral centres of Tristichopterus are said to be ossified 

 and the osselets of the lower lobe of the tail are described as 

 " springing from eight or nine interspinous bones," whereas in 

 Eusthenopteron the vertebral centres are not ossified and the caudal 

 osselets are articulated to the haemal spines. Moreover the bony 

 supports of the anal and second dorsal fins are much larger and 

 more fully developed in Eusthenopteron than they are in Tristi- 

 chopterus. Thus, in Eusthenopteron the length of the osselets of 

 the anal fin is equal to four-fifths of that of the apophysis to 

 which they are attached, and the breadth of the much dilated 

 outer end of the same apophysis is equal to rather more than 

 one-half its length. In Tristichopterus, on the other hand, the 

 osselets of the corresponding fin are less than half the length of 

 the apophysis from which they spring, and the slightly expanded 

 outer extremity of the apophysis is not much more than a third 

 of its entire length. 



The generic and specific characters of E. Foordi have been 

 drawn up from a number of more or less imperfect specimens. 

 The posterior half of the exoskeleton of the species is well seen 

 in a specimen about one foot long, in which, however, the caudal, 

 anal and second dorsal fins are imperfect. The bony supports of 

 these fins and about five inches of the vertebral column are beau- 

 tifully preserved and well exposed in another specimen. The 

 only parts of the head found so far are fragments of the jaw, 

 with teeth, and some isolated crauial plates, one of which is 

 evidently the operculum. 



In associating this species with the name of its discoverer, 

 the writer desires to acknowledge his obligation to Mr. A. H. 

 Foord for valuable assistance in the study of the various speci- 

 mens described in this paper. 



Glyptolepis microlepidotus, Agassiz. 1844. 



One specimen of a small-scaled Glyptolepis, which cannot at 

 present be distinguished from the above-mentioned species. The 

 fins of the side of the body exposed to view are well preserved 

 and one of the slender, acutely elongated and lobate pectorals is 

 clearly defined. The shape and sculpture of the cranial plates 



