1 1 2 CONTRIBUTIONS TO NORTH AMERICAN ICHTHYOLOGY IIT. 



process of reason in jjj not now cxp.iiinab'.e, Professor Agassiz identified 

 Ibis with tbe coniruon Chub Sucker of the West, a speeirs which I con- 

 sider Klentical with Cyprinu.s obl<»i;/us Mitchill. lie 1 bus transferred the 

 name Moxontonui from the '• Ited IJorso '' to tlie "Chub Sucker" group 

 Kafiuesque's description, however, renders it evident tliur his fish was 

 out' of the Red Horse kind; and as Moxontoma is the first generic name 

 applied to species of that group, it must be retained in spite of the 

 inconi|)h'teuess of the original diagnosis. 



Teretulus Kafinesque was proposed three pages later for ''nu extensive 

 subgenus, to which belong all the following species of Le Sueur: C.au- 

 reolus, C. )Nacrolcpidotus, ('. toiKjiro.struui, C. niyrieann, C. V'ttatus, C. 

 maenlosuSj C. fiucetta, besides the C teres and C. obh)iyn.s of ^litchill." 

 To these he adds his own species, C. melannps, C melaiiotus (= Campo- 

 stoma), C.fasciolaris, C. erythrurus, and V. Jlcxuosus. This ^'' omnium ya- 

 therum^^ receives the following diagnosis: — "Body elongate cUiudrical 

 or somewhat quadrangular, abdominal rays, dorsal tin commonly small, 

 tail equally forked." 



A nume proposed for a group of this kind, in the opinion of the pres- 

 ent writer, should not be set aside, but should be retained for some one 

 o; more of the si)ecie8 originally referred to it, and when any writer 

 adopts such a genus, he shall have the right to select any of the species 

 as its type, and the name should be considered thereafter as ai)plyiug 

 to siK-h typical species only, not to be revived in case sueLi typical species 

 be afterwards found to have had a prior generic name. In case no such 

 type has been selected by any author, then the "principle of exclusion'' 

 shouM be applied, aud the name be retained for such species as may be 

 left to the last, on subtracting from the mongrel group the diilerent 

 component genera in chronological order. 



In this view, Tcretnlus, having been by Professor Cope, in 1S08, re- 

 stricted to C. uurcolm Le S. and its ailines, these being congeneric with 

 species previously called Moxostoma, becomes a synonyuj ol Moxostoma, 

 and cannot be used for a distinct genus. The principle of exclusion, 

 if unmndilied, would rctjuire us to use the name Teretulus for those 

 species lefc on subtracting Catostomus proper, Moxostomn, Camjxistoma, 

 Erimyzou, and Jlypentelium, i. e., in i>lace of Minytrema. 



P(ycltosti)mi's Agassiz was pioposed htr this same j^roup, without 

 reference tothetuo names conferred by Jtafinesque. '1 his genus was 

 well characterized by I'rofessor Agassiz on the peculiarities of the scales 



