FI. AT- FISHES. 



43 



found. Increase in the number of like parts, such as scales, 

 fin-rays, and vertebrae, was alleged to be peculiar to, if not the 

 direct result of, the influence of an alpine or northern habitat; 

 and so many apparent verifications of the hypothesis had been 

 observed among species and closely related genera of wide dis- 

 tribution, that he had almost accepted it as a law of nature. 

 Conversely, a warm, or southern, habitat was thought to pro- 

 mote the reduction of the number of scales and fin-rays, and 

 lead to a shortening of the vertebral axis. 



The writer's investigation will be directed to but one of these, 

 namely, the fin-su[)ports; and for this purpose, and so that the 

 results may not be regarded as exceptional or due to individual- 

 ism in a few specimens, he will present for examination a large 

 number, selected at random from fish taken at different times 

 and places. It may be further a'ided that scores of others were 

 examined from time to time, which furnished exactly the same 

 evidence as the thirty or more of the following lists. 



The Winter Fh)under, Pleiironectes americanus Walbaum, is the 

 most abundant of the flat-fishes found in these waters. Eleven 

 are herein tabulated with the number of dorsal and anal 

 fin-rays : 



The average of these eleven specimens, fairly representative of 

 the whole species here, is: — Dorsal rays 61, Anal rays 45?. The 

 writer regrets the lack of personal knowledge of this, and the 

 other species referred to, as found in a more southern 

 range; but for purposes of comparison, he avails himself of the 

 data furnished by Drs. Jordan, Gilbert, and Evermann, whose 

 names are a sufficient guarantee of the scientific accuracy of 

 their statements. In "Fishes of North America, by David S. 



