142 ROYAL SOCIETY OF CANADA 



and being fed by cold alpine streams. They are, too, more rcx^ky, rapid, 

 and boisterous, especially in their upper courses, and afford only in the 

 lower stretches, and in brooks and ponds near their mouths, the degree 

 of quietness and heat most fresh-water forms, notably our cyprinids, 

 require. In the examination of these rivers a gradual decrease in the 

 number of species and individuals is also observed as one goes eastward, 

 and eventually nil jnirely I'resh-water forms disappear, not one being 

 met with in the Grand, York, or Dartmouth rivers. The cause does not 

 seem to be in the rivers themselves, for in character and temperature, 

 in the presence of warm ponds and lakes in their lower valleys, they are 

 similar to the others. The fact, however, may be accepted as evidence 

 of the small part birds and other accidental means play in the difTusion 

 of lish-life, and as confirming in part the theory which ascribes the 

 presence of certain small fishes in the upper rivers to an ancient east- 

 ward extension of the Restigouche. 



Catostomus commersoni, Lac. Big-scaled sucker. Carp (French). 



A widely distributed and variable form, occurring in the Grand 

 Cascapedia, Little Cascapedia, and Bonaventure rivers. Common also 

 in New Brunswick and in Nova Scotia (J. M. Jones). 



"While the stock of the Restigouche, including the Metapedia, and 

 all New Brunswick waters often shows a reduction in the typical 

 scale formula (10-65-9) and a lack of regularity in the labial papillae, 

 the deviation from the scale formula is more marked and constant among 

 the Gaspé fish. Here it is 9-60-7, a divergence not at all important so 

 far as the number of transverse series (60) is concerned ; but the 

 decrease in the longitudinal rows is significant ; for, as the fish are 

 robust and attain a length of eighteen inches, the scales are relatively 

 larger. Were this form, however, derived from typical commersoni, 

 variation of an opposite character might be looked for, as the genesis, 

 size, and arrangement of the scales are more or less correlated with the 

 degree of bodily activity life in a given medium requires ; so that a 

 reduction in the size, but an increase in the number is the usual result 

 of active movements, rapid currents, low temperature, and alpine or 

 northern distribution. The ancestors of this sucker may have been of 

 lacustrine habit, and closely related to commersoni. It was a disappoint- 

 ment not to find in the Gaspé rivers C. longirostris, LeSucur, the Long- 

 nosed, or Northern, Sucker, not uncommon in the St. John river, N.B. ; 

 nor does it seem to occur in the Restigouche or Metapedia. 



