Dec. 28, 1916. FisHes or PANAMA— MEEK AND HILDEBRAND. 235 
Unless there were not enough specimens at hand, not fewer than ten 
were measured, and in many instances where the measurements were 
of special importance a much larger series was used, selecting as a rule 
as wide a range in size as possible. The counts of fin rays, scales, etc., 
are based upon similar series. 
Such an expression as the following, occurring at the beginning of 
the description of nearly every species, “Head 2 to 3.5; depth 3 to 3.8,” 
signifies that the length of the head, measured from the end of the snout 
to the bony margin of the opercle, is contained 2 to 3.5 times and that 
the greatest depth of the body is contained 3 to 3.8 times in the length 
of the body from the end of the snout to the base of the caudal fin. In 
giving the number of fin rays Arabic numerals are used to indicate the 
number of soft rays and Roman numerals the number of spines. For 
example, D. IV-I, 16 signifies that in this instance there are two dorsal 
fins, the first being composed of four spines and the second of one spine 
and sixteen soft rays. If these spines and soft rays were included in a 
single fin instead of in two fins, the result would be written thus; D. V, 16. 
For the purpose of ready identification artificial keys to the families, 
genera and species are introduced. In using them, first determine which 
of the major groups the species is in and then take up the regular order 
of letters under each group. If the characters of the specimen in hand 
do not agree with those given under the single letter, look under the 
same double letters, ignoring all intervening matter. 
