;[54 ^^ PARNELL'S LIST OF 



migration to the sea, when they are observed six and a half, seven, and even 

 eight inches in length. 



After they reach the sea they are lost sight of until the middle of the follow- 

 ing July, when they are seen in their return to the rivers, from ten to twelve 

 inches in length, under the name of Herlings or Whitlings. 



The herlings, so far as I have observed, remain in the rivers until the end 

 of December or beginning of January, and return again to the sea. In June and 

 July they reappear, being from a pound and a half to two pounds in weight, when 

 they are named Sea-trout, and are now of suflBcient size to reproduce their species 

 in the following October. 



Salmo csecifer,* Parnell. Salmo levenensis, Walker. — Lochleven Trout. Com- 

 mon in Lochleven. 



This species of trout, which is well known to many persons as a delicate 

 article of food, is considered by most naturalists as a variety of the Salmo fario or 

 common fresh- water trout, the redness of its flesh depending on the nature of 

 its food. 



I consider it, however, not only as distinct from the Salmo fario, but as one 

 of the best defined and most constant in its characters of all the species hitherto 

 described. It is at once distinguished from the common fresh- water trout by the 

 number of its csecal appendages, which varies from sixty to eighty, whereas in 

 the S.fai'io they are never more than forty-five or forty-six in number. Its tail 

 is crescent-shaped at aU ages, and its body has never a vestige of a red spot. The 

 tail of the common trout is sinuous, and at length even at the end, and its body 

 is almost always marked with red spots, besides its flesh being always of a white 

 appearance. (See Plate VIII.) 



I have no doubt but that more than two species of trout are to be met with 

 in our freshwater streams, which at present receive the name of Salmo fario. 



Salmo Salmulus, Yai'r. — Parr. Common in the river Forth. Though the 

 parr is stated by Ichthyologists as a distinct species of trout, yet characters have 

 not hitherto been given, by which it is to be distinguished either from the young 

 of the sea-trout or from the young of the salmon, and it is from the want of some 

 constant specific character that the parr has been so often mistaken for the young 

 of the salmon. 



If a young salmon of eight inches in length be compared with a parr of equal 

 size, they wiU be found to differ in the following respects (See Plate VIII.) : 



The pectoral fin of the parr is large and dusky at the end, measming one- 

 fifth of the length of the body, exclusive of the caudal rays. The same fin in the 



* Bearing caeca, — the caeca being more numerous than in any of its congeners. 



