CYPRINID^ OF EASTERN CANADA. 43 



Semotilus bullaris Raf. 



Silver C'liiili. 



This species has a less extensive and cnntii.uous distribu- 

 tion than the last, being confined entirely to the Atlantic slope. 

 It is seldom met Avith, like afromaculatus^ in the smaller 

 and more boisterous tributaries of rivers, and is, conse- 

 quently, less able to pass from one river system to aiiutiier and 

 attain in time a wide and continuous distribution, 'ibis seems 

 to be the only reason for its absence from certain waters well 

 suited to it, and favorably situated to be stocked from others 

 adjacent. Ballnris is one of the most common tishes to be met 

 with on the St. John River, the upper courses of which are in- 

 terlaced with tributaries of the Restigouche, in a comparatively 

 level district, yet it is not known to occur in the latter, nor in the 

 Metapedia, where it was industriously sought after by the writer 

 in the summer of 1898. Neither does it occur in any of the Gaspe 

 rivers, and the writer failed to find it in the Anna[)olis and La 

 Have rivers, N. S., in IS'JV), when he made a careful exaujmation 

 of thjse waters. 



Restriction to a fni'.ly uniform environment may better ac- 

 count for the absence of that variation, so characteristic ot'fttromacu- 

 latus, than that S( metimes assigned, namely, the great antiquity 

 of the specie.^. This is said to result in such an equilibrium of 

 the specific characters as imparts greater stabilit}' and less ten- 

 dency to variation, rendering the creature not so responsive to in- 

 fluences of new environniGiits. Though formally inclined to ad- 

 mit this principle of stubborn balance and attribute to it a cer- 

 tain degree of conservative force, as he extends his inquiries and 

 investigation, the writer is becoming more and more convinced 

 that the creature is bat tha vitalize., h.siory of its environment. 

 That bullaris, then, shows a greater degree of st;.bility in its speci- 

 fic characters than many of our cyprinids seems, at least in east- 

 ern Canada, due to the uniformity of its habitat. 



The only variation noticed by the writer in this species is 

 met with sometimes aniorg immature specimens, four - or five 

 inches long, and consists in the development of an intensely 



