. British and Irish Salmonidæ. Salmonidae. 222 SALMOI^IDuS: OF BRITAIN. Teeth.—Of moderate strength, and wliicli it has been asserted exist in this form on the vomer in a single series, and persistent throughout life, but in a double row in burn trout of the same size, but we have first to consider whether the facts as stated are correct. All trout and salmon (not chars) when young, irrespective of the teeth on the head of the vomer, have (as has been already remarked) a double row along its body, but these in all, dependent on age or rapidity of groAvth, fall out, commencing behind and exten
. British and Irish Salmonidæ. Salmonidae. 222 SALMOI^IDuS: OF BRITAIN. Teeth.—Of moderate strength, and wliicli it has been asserted exist in this form on the vomer in a single series, and persistent throughout life, but in a double row in burn trout of the same size, but we have first to consider whether the facts as stated are correct. All trout and salmon (not chars) when young, irrespective of the teeth on the head of the vomer, have (as has been already remarked) a double row along its body, but these in all, dependent on age or rapidity of groAvth, fall out, commencing behind and extending forwards. In salmon and sea trout, which are forms which grow most rapidly, these teeth are shed the earliest, while the Lochleven trout, which is likewise a rapid grower, loses them rather sooner than the burn or loch form, while to say that in the mature they are invariaUy in a single row is erroneous. At the same time it is not here advanced that rapidity of growth is the sole cause of this, but the deciduousness of the teeth appears to be owing to the absorption or narrowing of the tooth-bearing ridge on the vomer, in consequence of which, fix'st from being in pairs, they become in a single row and finally fall out. {See fig. 45, page_197 ante.) In the following seven specimens of Lochleven trout the condition of the vomerine dental system was as follows :—In a female 20 inches long, 2 teeth exist on the hind edge of the head of the vomer, and 3 along the front half of its body, the two first of which are almost opposite one another. (2) In a male 9 inches long, 2 teeth at hind edge of vomer, 2 at the front end of the body, and 7 in an irregular zigzag line, almost in one continuous row, while their points turn. Fig. 50. Outlines, life size, of tail fius of Lochleven trout reared in ponds at Howietoun. 1, at 2 months old: 2 and 3, at 13 months : 4, male, 10 mouths : 5, 6, 7, males, at 30 months. From specimens in the British Museum collection : 8, female, 12 in.
Size: 1510px × 1655px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1880, booksubjectsalmoni, bookyear1887
