1856.] 167 



afterwards appeared a Synopsis of the Ichthyologkal Fauna of the Pacific slope of 

 North America, chiefly from the collections made by the U. S. Expl. Exped. under the 

 command of Capt. C. Wilkes, tvith recent additions and comparisons with eastern types. 

 By the same author* 



These two papers, though anticipating some of the following results, were 

 greeted with a hearty welcome, and I can only regret that the second was not 

 concluded up to the time I am writing. I have delayed entering into this sub- 

 ject as long as was consistent with the duties imposed upon me. 



In both of them, we find the laudable desire of attempting to bring back into 

 use, the long forgotten genera of Rafinesque, which fell into disuse because of 

 their own imperfection; and if they have not passed into the common nomencla- 

 ture of the day, it was owing to their defect, more than to the partiality of 

 naturalists. For we may well imagine how anyone would feel when rebuilding 

 another's work, as little known to the author as to the commentators themselves. 



And yet, for my part, I have always looked upon the restoration of Rafinesque's 

 genera and species as highly desirable, so soon as they had once been proposed 

 and introduced into science as names. But in order to do justice to the scheme, it 

 was necessary to the undertaking that one should go to the very ground trodden 

 over by Rafinesque himself, his book in hand, during all the seasons of the year, 

 ay, even for years in succession, to enable us to discriminate between that which 

 Rafinesque really observed, and that which is imaginary. 



That the Ichthyoloyia Ohiensis has been, and still is a stumbling block, is fully 

 evinced by the fact that Dr. J. P. Kirtland, the Ohio ichthyologist, of untiring 

 and energetic zeal and perseverance, was baffled in many of his attempts to 

 determine Rafinesque's genera and species. 



These genera and species, thus restored by Prof. Agassiz, may therefore not 

 be received by all ichthj'ologistsas the final settlement of that much controverted 

 question. Be it as it may, that is : whether the identification be right or wrong, 

 since we must have these names, I sincerely hope Ihey will now be adopted, 

 once for all, as proposed. 



Since circumstances have compelled me to write this memoir before the com- 

 pletion of Agassiz's synopsis, I have restored the balance of Rafinesque's genera 

 in the family of Cyprinoids: such are Plargyrus and Semotilus. Once upon that 

 field of inquiries I reverted to Heckel's genera Argyreus and Leucosomus, and 

 shewed their claim for admission upon the same general principles and canons 

 of scientific nomenclature. 



On a former occasion the genus Leucosomus was altogether misunderstood by 

 me, and from an advice of mine it thus entered into the " History of the Fishes of 

 Massachusetts, by Dr. D. H. Storer." Prof. Agassiz was led into the same 

 error. f Heckel by inadvertence applies the name of Cyprinus chrysohucus, 

 Mitch., to Leuciscus pulchellus, Storer, as shown by the figures given of its teeth 

 and the wording of its generical diagnosis. Leucosom.us, therefore, is identical 

 with Chdlonemus, and accordiagly is the name to be adopted. Cheilonemus was 

 liroposed tor Leuciscus jmlchellus, and allied species, when it was supposed that 

 Leuciscus chrysoleucus would constitute the type of the genus Leucosomus. But 

 it is now well ascertained that Leuciscus chrysoleucus of Mitchell belongs to 

 Rafinesque's genus Luxilus ; and Luxilus has the priority over Leucosomus. 



Leuciscus gracilis of Richardson, referred by Heckel to Leucosomus, is of a dif- 

 ferent generic type. 



As to the genus Argyreus, Heckel includes in it two species generally distinct. 

 Cyprinus atronasus, Mitch., and Cypr. rubripinnis, Mus. Par. MS. But Cyprinus 

 rubripinnis is identical with Leuciscus cornutus, and since Leuciscus cornutus is to 

 enter the genus Plargyrus of Rafinesque, Cyprinus atronasus remains as the 

 type of the genus Argyreus, which again is identical with Rhinichthys. It must 

 be recollected, however, that the teeth figured by Heckel under the name of 

 Argyreus rubripinnis, are those of Plargyrus cornutus. 



*Amer, Jour, of Sc, 2d. ser. xix. 1855, pp. Vl, 215. 

 j-Amer. Jour, of Sc, 2d. ser. xix. 1855, p. 225. 



