FISHES OF LAKE SUPERIOR. 277 



the eye. Their form and direction are not quite the same as in 

 the preceding species. 



The shields of the dorsal series are sixteen in number, cordi- 

 form as in the preceding species, but longer than they are broad, 

 approaching however more to a circle. The right and left mar- 

 gins are equally denticulated. An odd plate of medium size is 

 situated behind the dorsal, and behind this latter a pair of much 

 smaller plates fill up the remainder of the space to the anterior mar- 

 gin of the caudal. Both are carinated and provided with a hook. 



The lateral series consists of thirty-five pairs of plates, elon- 

 gated, narrow, irregularly triangular, the most acute point directed 

 upwards, much resembling those of the preceding species. 



The abdominal series has from eight to nine plates, generally 

 more irregular, more strongly denticulated, with a strong carina 

 and prominent hook. 



The articular bone of the pectoral fin is stronger and more 

 widened. The pectoral fins themselves are longer and more 

 rounded on their posterior margin. The anal is also more narrow. 

 The other fins resemble each other excepting the caudal, which 

 seems to be less furcated. We have not been able to make a 

 fuller comparison of the two species, having had only a dried speci- 

 men of the latter in our possession. The following formula of the 

 rays is only an approximation, as the fins are somewhat defective. 



'P. I, 32* or 33; V. 26;'D. 34; A. 25. C. lower lobe one 

 hundred and more. 



Very distinct fulcra exist along the anterior margin of all the 

 fins, with the exception of the pectorals. 



Habitat, Sault St. Mary. 



ACIPENSER RUPERTIANUS, Richardson. 



This species, which we did not find in our excursion, is men- 

 tioned here only incidentally, for comparison with those which we 

 have described. Richardson has figured and described it in his 

 Fauna Boreali-Americana. Our comparisons have been made 

 upon a skin from Sault St. Mary, for which I am indebted to 

 Mr. McLeod. 



