34 
OF FISHES IN GENERAt. 
allow four or five times that fpace for the period of its 
life, it will not exceed thirty years. 
Dilferent methods have been devifed for afcertaining 
the age of fillies, feme of which will, perhaps, pretty 
accurately determine this matter. The ingenious Mr. 
Hiddojlroam, a Swede, has attempted to compute their 
ages by the number of concentric circles obferved in a 
tranfverfe fection of the vertebrae of the back ; and it has 
been found, that each circle, like that in the feftion of 
a tree, correfponds to a year of the animal’s life. In 
confirmation of this fact, experiments have been made on 
different individuals of various (i7.es, but or the fame age, 
whole concentric circlss have always been of an equal 
number; whereas a young filh differs from an older one 
of the fame fpecies, by having a fmaller number of thefe 
circles. By this method of computation, feveral filh 
were found from fifteen to twenty years, but none gave 
indications of a greater age. 
Another method of computing the age of fillies, prac- 
tifed by M. de Bufon, is by numbering the concentric 
circles upon their feales* ; but as this requires a more 
minute examination, it is, of confequence, liable to 
greater uncertainty. On examining the fcale of a filh 
through a microfcope, it exhibits a number of circles, 
one within another, refembling tliofe in the vertebra of 
the back, and, like them, every circle reprefents a year 
of the fi Hi’s life. A fcale of a carp, thus examined, an- 
nounced the animal to be no lefs than an hundred years ; 
a longevity lefs incredible, becaufe confirmed by the tef- 
tiir.ony of feveral different authors f, fome of whom have 
aliened, that this filh lives twice that period. 
f Vide Hilt, gener. et part. 
j Gefner and Albcttus. 
