558 MR SHAW'S EXPERIMENTAL OBSERVATIONS ON THE 



of species in their earlier stages, recourse has been had to very fanciful and ill- 

 defined attributes ; and I am of opinion that in almost every instance these vague 

 characters have been applied to individuals of the young of the real salmon, of 

 which the characters had not been so fully developed as those of others, rather 

 than to the young of any distinct species. With the view, therefore, of affording 

 scientific men an opportunity of comparing the young of the salmon trout with 

 that of the salmon, with which they are supposed to have been confounded, I have 

 taken this opportunity of la3dng before the Royal Society a brood of the former 

 produced by artificial impregnation, and exhibiting five successive stages, from the 

 day on which they were hatched to the age of nine months, accompanied by the 

 skins of the parent fishes. At the age of six months they bear no very marked 

 resemblance to the young of the real salmon either in the parr or fry state, and 

 as they advance in age and size, the resemblance becomes still slighter. How- 

 ever, on comparing them with the common trout, the resemblance is very striking, 

 the general outline of the fish being much less elegant than that of the young 

 salmon or parr, the external markings being also more peculiarly those of the 

 trout species, so that, in the absence of the parent skins, it would be a matter of 

 difficulty to determine to which kind of trout they actually belong. A speci- 

 men of the young common trout of this season's produce, taken from the Clyde abom 

 the Falls^ is also exhibited ; so that the young of the three species most common 

 to this locality (and of corresponding age), viz. Salmo salm\ Scilmo trutta, and 

 Salmo fario, may be carefully compared. The ova of the Salmo eriox, which is 

 less common in these tributaries, I have not as yet had an opportunity of experi- 

 menting upon. 



To resume my history of the so-called parr. Having brought the series of 

 experiments on the ovum of the salmon, begun in January 1837, to a satisfactory 

 conclusion, it may be gratif3dng to those who have taken an interest in this cu- 

 rious inquuy, to be put in possession of the results. I have already detailed the 

 particulars regarding the mode practised in captming the parent salmon, the pro- 

 cess of fecundating the ovum artificially with the milt from the male, and the 

 appearance it presents fi*om that period up to the exclusion of the young fish 

 from the capsule of the ovum, which took place on the 7th of May — 101 days 

 after impregnation. A complete series of specimens from the Qgg until the com- 

 mencement of the third year, illustrates the following descriptive notes. 



Specimens taken fi'om the pond, when ten days old (16th May), had still 

 a considerable portion of the vitelline bag attached to the abdomen. Specimens 

 removed when forty-eight days old (24th June) had no recognisable bag, but the 

 symmetry of the form was as yet but imperfectly developed. After the lapse of 

 two months (7th July) the shape was found to be materially improved, and to 

 exhibit in miniature much of the form and proportions of a mature fish. At the 



