. British and Irish Salmonidae. Salmon. 8 SALMONID^ OP BEITAIN. certain local varieties or races. If, however, the variations are not of a persistent character, nor exceed the differences between the limits laid down for a species, tHese cannot be considered as indicating a distinct species: for to render such valid, we must have a permanence of variation from the original form. Thus among the sticklebacks w-e find in the ten-spined form, some possessing ventral fins others destitute of them; but this difference not being permanent merely resolves itself into a local race or inconstant variety
. British and Irish Salmonidae. Salmon. 8 SALMONID^ OP BEITAIN. certain local varieties or races. If, however, the variations are not of a persistent character, nor exceed the differences between the limits laid down for a species, tHese cannot be considered as indicating a distinct species: for to render such valid, we must have a permanence of variation from the original form. Thus among the sticklebacks w-e find in the ten-spined form, some possessing ventral fins others destitute of them; but this difference not being permanent merely resolves itself into a local race or inconstant variety. The number of vertebra and the caecal appendages have been considered as characters which may materially assist m fixing the locaHty of a species among the Salmonidm, and it is proposed m detail some of the various structural and functional differences that have been brought forward for the purpose of establishing species among the true salmon, Salmones. It has occurred that owing to too great importance having been given to inconstant variations the number of species among this family has been unduly augmented, and varieties have been accorded specific rank: while every little variety of form, colour, or structure has also been reckoned as possibly demonstrating hybridity lnnJJ'%^'^?.°'f*^-''' °* l^^^^''* P*"*' °^ *^^ ^°^J ^^^y ^^^ age, season, or locality,* and^this may be augmented in some anadxomous forms which have been subjected to unnatural retention in fresh water, insufficiency of food or ti?fpT«f°°'^"^iT^?'- , The head of the male is generally longer than that of. SIAIiE OB KETTLE Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Day, Francis, 1829-1889. London, Williams and Norgate
Size: 2060px × 1213px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, bookpublisherlondo, bookyear1887
