238 



Part III. — 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 (pi. XI] I.). 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"9cm. to 

 13'lcm. (3|M>^ 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 105cm., and the arithmetical average 

 0 lcm., or 4 inches. 



The next group numbered 32, varying in size from 14cm. to 19*lcm. 

 (5^-7| inches), and were a year older, on an average about 1 year and 11 

 months. The maximum number were at 16*5cm., the mean was 16cm., 

 and the arithmetical average 16*21cm., or 6| inches. The growth from 

 the previous series was thus about 6'lcm., or 2|- inches, which represents 

 the increment in a year. 



The third series numbered 20, the range was from 19*6cm. to 24* lcm., 

 (7|-9^ inches), the maximum number were at 21cm., the mean was 

 21 -3cm., and the arithmetical average was 21'54cm., or 8£ 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^ inches. 



The fourth series numbered 14, varying in length from 25 # 2cm. to 

 28*9cm. (9|f-ll§ inches); the maximum number were at 27cm., the 

 mean was 26*5cm., and the average 27cm., or 10§ inches. The indicated 

 growth in a year amounted to 5*46cm., or 2^ inches. These gurnards 

 were approximately four years old. 



A fifth series consisted of 13 fish, varying from 29*7cm. to 32 -5cm. 

 (11|-13| inches); the maximum number were at 30cm., the mean was 

 31cm., and the calculated arithmetical average was 30*97cm., or 12j 

 inches. The growth from the previous series was about 1| inches, and 

 the age of the series nearly five years. 



Towards the end of July another collection from the Firth of Forth was 

 examined (pi. XIII.). The first series of 32 varied from 11cm. to 13'7cm. 

 (4|-5| 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 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 20'2cm. (5|-7j| inches) ; the maximum number were at 

 16'5cm., the mean was 17cm., and the average was 17'lcm., 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 21cm. to 26'5cm.; the 

 maximum number were at 22'5cm., the mean was 23*5cm., and the 

 calculated average 23'3cm., or 9 T 3 ^ inches. These fish were about three 

 years of age, and the growth indicated from the previous series was 62cm., 

 or 2 T 7 ^ inches, which is too great. 



In the August collection (pi. XIII.), the first series included 78 gurnards 

 from 10 f 8cm. to 15'6cm. (4|-5| inches); the maximum number or mode 

 was about 13cm., which was also the mean, while the computed average 

 was 13*1 4cm., or 5^ inches. These fish were about 13 or 14 months old. 



The second series numbered 33 fishes, the sizes ranging from I6'4cm. 

 to 22-6cm. (6|-8| inches) ; the maximum numbers wore at 20cm., the 



