\ 
442 Dr. broussonet’s Account of 
fhort from any one part to another, would anfwer the fame 
purpofe ; but if you take the terms of the meafures, and 
compare them one with another, or all of them to a tingle 
one, a method may he deduced for determining the fpecies, and 
defcribing each with accuracy, and that is the method which 
I ufed. 
There is no doubt that filhes have a regular growth, and that 
all their parts have a proportional increafe : it is therefore of 
no confequence whether the meafure be taken from an old 
or a young fubjed, it will be always of the fame ufe for 
determining the fpecies. The term to which I refer all the 
reft, is taken • from the diftance between the apex of the 
upper jaw, and the balls of the fin of the tail. The extremity 
of the upper jaw is the point from which I take the dis- 
tance to all the other parts. To determine with more accuracy 
the junction of the fin to the tail, I incline the fin fo as to 
form an angle with the tail ; 1 take the diftances with a pair of 
compafies, to avoid the irregularities of the furface of the body, 
which are infinitely various. When I have taken the diftance 
with the compalfes, I make a reference to a rule, which is 
divided in Englifh inches, each of them fub-divided in tenths. 
To exemplify my pradice in a fifh of the fuppofed length of 
40 lines from the upper jaw to the tail, and from the fame 
point to the anus of 20 lines, I fay, that the didance from the 
head to the tail compared with the didance from the head to 
the anus is in this fpecies as 40 to 20, which I exprefs in 
this manner : Lc. : A :: 40 : 20, which I thus reduce, 
Lc. : A :: 10 : 5. I then take the length from the upper jaw 
to the beginning of the dorfal * fin, and to its end : next from 
* I meafure the dorfal and anal fins at their balls, never in their margin. 
the 
