238 Part IIl-—Twenty-fourth Annual Report 
In many of these cases the division into groups is obvious. A few of 
them may be considered in detail, in order to make clear the rate of 
growth. 
In the Firth of Forth, in May, from 9th to 13th, a number of gurnards 
were taken, belonging to at least five annual series (pl. XIJI.). The 
smallest, representing the fishes from the previous year’s spawning, and 
being therefore from seven months to fully a year old, and principally 
about eleven months, numbered 21, They varied in size from 7-9cem. to 
13-lem. (33-54 inches), a range or difference of 5:2cm.; the maximum 
number measured about 9cm. (the apex, mode or maximum ordinate, of 
the curve), the mean was about 10°5cem., and the arithmetical average 
O-lem., or 4 inches, 
The next group numbered 32, varying in size from 14cm. to 19°lem. 
(53-74 inches), and were a year older, on an average about | year and 11 
months. The maximum number were at 16‘5cm., the mean was 16cm., 
and the arithmetical average 16°2lcem., or 62 inches. The growth from 
the previous series was thus about 6:lem., or 23 inches, which represents 
the increment in a year. 
The third series numbered 20, the range was from 19°6cm. to 24:1cem., 
(73-91 inches), the maximum number were at 2lcem., the mean was 
21:3cm., and the arithmetical average was 21°54cem., or 84 inches. These 
fishes were very nearly three years old, and the growth indicated in a year 
from the preceding group was 5°3cm., or 2,1, inches. 
The fourth series numbered 14, varying in length from 25:2cm. to 
28°9em. (915-118 inches); the maximum number were at 27cm., the 
mean was 26°5cem., and the average 27cm., or 103 inches. The indicated 
erowth in a year amounted to 5°46cm., or 24 inches. These gurnards 
were approximately four years old. 
A fifth series consisted of 13 fish, varying from 29°7em. to 32‘5cm. 
(112-13? inches); the maximum number were at 30cm., the mean was 
3lem., and the calculated arithmetical average was 30°97cm., or 123 
inches. ‘The growth from the previous series was about 14 inches, and 
the age of the series nearly five years. 
Towards the end of July another collection from the Firth of Forth was 
examined (pl. XIII.). The first series of 32 varied from 1lem. to 13:7em. 
(43-53 inches), and was obviously incomplete by the absence of many of 
the smaller gurnards, the range of sizes amounting to only 2-7cm. The 
maximum number were at 12-5cm., the mean was the same, and the 
average 12°4cm., or 415 inches. These fish were probably rather over one 
year of age. 
The second group was represented by 107 gurnards, ranging in length 
from 14*3cm. to 20:2em. (53-742 inches) ; the maximum number were at 
16‘5cem., the mean was 17cm., and the average was 17-lem., or 6? inches. 
The indicated growth from the previous generation was 4°7cm., which is 
too small, owing to the reason stated—the absence of the smaller fishes. 
The next group numbered 12, varying from 2lem. to 26°5cm.; the 
maximum number were at 22'5cm., the mean was 23°5cm., and the 
calculated average 23:3cm., or 953, inches. These fish were about three 
years of age, and the growth indicated from the previous series was 6°2em., 
or 2,'. inches, which is too great. 
In the August collection (pl. XIII.), the first series included 78 gurnards 
from 10°8em. to 15‘6cm. (44-52 inches); the maximum number or mode 
was ahout 13cm., which was also the mean, while the computed average 
was 13:14cm., or 53 inches. These fish were about 13 or 14 months old. 
The second series numbered 33 fishes, the sizes ranging from 16-4cem. 
to 22:6em. (64-83 inches); the maximum numbers were at 20cm., the 
