CYPRINID^ OF EASTERN CANADA. 30 



4. Rhinichthys cataracts ( Val. j Jordan. 



Loni>-no8e<l Dace. 



5. R. atronasus ( Mitch. ) Ag. 



Blunt-nosed Dace. 



These two specie.s are with us very closely related, and pre- 

 sent at all times such an instability of characters as to suggest 

 intergvading. In fact no typical dace of either alleged species, 

 as they are represented and described from the United States, 

 occur in eastern Canada as far as the writer's experience go^s, 

 and he has collected all over the Maritime Provinces, including 

 a portion of Quebec. All ours have the 8-rayed dorsal, charac- 

 teristic of cntaractx, the dark lateral band marking atronnsus, the 

 small size, too, of the latter, but an increased scale formula ap- 

 proaching, but never equalling, that ascribed to the former. Our 

 representative of ntronrisus is peculiar in having a narrow 

 silver_y band bordering the black lateral one above — a feature 

 nowhere else ascribed to it. 



Couesius (Ceratichthys) Jordan. 



The genus is widely distributed in North America, consist- 

 ing, however, of only a few closely allied species, whose differ- 

 entiation is made to rest upon such slight and varying charac- 

 ters as to render the classiHcation a mere recognition of ihe ex- 

 tremes of variation, blending with each other througn a series of 

 intermediate forms. For the purpose of illustrating this point, it 

 is only necessary to compare the three most marked northern 

 forms, ('. plumbeiis Gunther, C dissiniilis Girard, ; nd C. gneni 

 Jordan. The first is our alleged eastern form; the second pecul- 

 iar to Lake Superior and the northern and northwestern p )rt.ou 

 of the Mississippi basin ; the last a recently described species 

 from Fort St. James, B. C. (Bull. Nat. His. Soc. of B. C, 18J3.) 

 The element of chief value, indeed of any value, is the scale 

 formula, which is as follow'S : — 



C. grecni Jordan. 10-57 7. 



C. plumheus Agassiz. 11-65-7 (11-60 to 70-7 j. 



('. f/is.Nim/fe Girard. r2-()S-S. 



