HAUNTS AND HABITS. 107 



according to the opinions of what I deem the best authorities, 

 there is but one distinct species. 



Endless attempts have been made in England to distinguish 

 and define fresh species; but these have, in my judgment, all 

 failed. According to Mr. Agassiz, whose opinion on this sub- 

 ject I consider paramount to all others, the Gillaroo, or Gizzard- 

 trout, as it is sometimes erroneously called by the Irish, and 

 some of the Scottish writers, is merely a casual variety of the 

 Salmo Fario. The distinction, which consists principally in the 

 thickness and induration of the stomach, having arisen from 

 feeding on shell-fish, in the first instance, in individuals, has 

 been gradually ingrafted on generations, until, in process of 

 time, it has become a permanent type. 



Although this variety is not known to exist on this continent, 

 I have a very strong suspicion, from many circumstances which 

 I have heard, on good authority, concerning the Trout of the 

 Marshpee river, in Massachusetts, that on examination, it will 

 be found to possess some of the leading peculiarities of this fish, 

 particularly the indurated stomach. I have never had an oppor- 

 tunity of seeing the Trout of this river ; but I know that it has 

 many peculiarities of habit resembling those of the Gillaroo, 

 especially that of feeding on shell-fish, a friend of mine having 

 actually succeeded in taking them with small white crabs, at a 

 time when they would look at no other bait. 



I mention this, merely by way of suggestion, as offering an 

 interesting subject of investigation for naturalists. 



Sir Humphrey Davy, in his " Salmonia," rather leans to the 

 idea that the Gillaroo is a distinct species, though he leaves 

 it uncertain whether it may not be a permanent variety ; his 



