168 [September, 



All the species referred to in this memoir I have seen and examined ; there 

 is not a solitary fact here recorded that was not theresult of personal researches. 



On several occasions I have referred to species from the Atlantic States of the 

 Union, and even from the northern lakes, but it will be obvious to every one that 

 it was only on such occasions as could not well be omitted without sacrifice to 

 the completeness of the subject. 



I have aimed at concision, as far as consistent with the nature of the task. 

 It was deemed unnecessary to recall, ever and anon, the history of any parti- 

 cular genus, unless it happened to be intricate, for, whoever is interested in 

 the subject, is sufBciently familiar with it. It would be different were I to 

 write a popular work on our fishes. 



In the diagnosis of the genera I have often repeated characters shared by many 

 of them; these repetitions I am convinced are needful to their proper under- 

 standing. It may not appear so to a few ichthyologists; but I write 

 for naturalists, for the reader who seeks &fter general information. Besides, 

 the method I follow is the natural, the true method, that which has superseded 

 the artificial method of the last century. In describing the teeth, I have adopted 

 Heckel's phraseology, since it appears to me to answer to the present wants of 

 Ichthyology. 



The coloration, as a general rule, is described from specimens preserved in 

 alcohol, in which the brilliancy of the hues is seldom preserved, and occasionally 

 quite altered. 



In the course of these investigations I have carefully compared the fishes of 

 our hemisphere to those occurring in the waters of the eastern hemisphere ; and 

 when genera and species, either of fishes or reptiles, have, at any time, been 

 described as new, it was the result of such comparative study, shunning display 

 of loose erudition and false criticism, which too often leads into error the true 

 observer. 



I have thus added many new genera and species to the known lists. This 

 cannot be surprising ; a country so vast as North America, ii-rigated by so many 

 branching streams and large bodies of waters in the shape of lakes and numer- 

 ous ponds, a country comparatively little explored, was to yield many species 

 unknown to our predecessors in the field. A superficial knowledge of the his- 

 tory of ichthyology in North America, would at once explain how it is that a 

 "Synopsis of the Fishes of North America," published in 1846, should not have 

 proved a full and complete record of all existing fishes of the country : a synopsis 

 which, moreover, only professes to give such species as were known at that time. 

 If we are so fortunate as to be able to add to the known catalogue of genera and 

 species, let us not lose sight of both the time and the circumstances under 

 which we have accomplished it. Recriminations, in that respect, are not likely 

 to advance much our knowledge on the subject, and furthermore, it j^laccs a 

 co-temporary exactly in the same situation towards the next coming generations 

 as the former generations hold towards him. 



Most of the new genera which I propose have been designated by words taken 

 from the North American Indians, as being more euphonic than any one I 

 might have framed from the Greek. The classic literature has already furnished 

 so many names that there are but few instances in which a name might yet be 

 coined and express what it is intended to represent. I offered this remark as a 

 mere statement ; not as an apology. 



OYPRINI. 



But two genera of this group or tribe, whichever called, are included in this 

 memoir. And curious to say one is provided with a buccal barbel, and the other 

 not. The presence or absence of barbels, therefore, does not seem of- primary 

 import here. The teeth are of the molar kind (^Dentes molares), of the grinding 

 type (D. masticatorii), without grooves or ridges, and are disposed upon two 

 permanent and a third, deciduous rows: 3 2 | 5 5 | 2 | 3. The ventrals are 

 nserted in advance of the anterior margin of the dorsal. 



