208 THOMAS BARBOUR. 



rate of growth would seem reasonable enough. Emphasis is laid 

 on this point luvunse great search has been made for the young 

 during the months of spring and early summer. This search 

 has been fruitless, while these inch-long fishes were got in Sep- 

 tember. 



The drawings which have been made by Mr. E. X. Fischer 

 with special regard to the proportions, show three aspects, dorsal, 

 lateral, and ventral of the 37 mm. example, as well as of one 80 

 mm. long; two aspects of a fish 130 mm. long and a lateral view 

 of a three-foot adult. These figures serve to show the remarkable 

 features of the young as will as the changes in form which the 

 species undergoes during growth, better than would a lengthy 

 verbal description. 



As may be readily seen from the drawings the most interesting 

 characters to be observed in the young are the short sturgeon- 

 like snout which has not yet become in the least spatulate; the 

 extremely heterocercal form of the tail; the relatively long bar- 

 bels and the less developed fins throughout. Unfortunately the 

 notch near the outer extremity of the caudal fin is not shown n 

 the very young because of the frayed margin of the tail fin. 

 This character is marked in the slightly larger examples and, 

 as is shown in the lateral view of the 80 mm. specimens, the notch 

 marks the point where the cartilag nous fin rays cease to be 

 developed. This character would seem to suggest that seen in 

 the caudal fins of certain sharks w r here there is a similar notch. 

 The whole general form of this, the smallest known selacho- 

 stomous ganoid is certainly most strikingly shark-like as well as 

 reminiscent of the adult forms of other ganoid genera. 



