76 Part LIT —Twenty-first Annuai Report 
In males of 109, 99, 96 mm. the testes were small and solid. 
On 24th May no females contained ripe or large eggs. In one of 
122 mm. the yolked eggs measured up to *35 mm.; in another of 
117 mm. they reached nearly the same size—viz., ‘33 mm.; in one of 
70 mm. they measured up to ‘17 mm. 
On 26th June females ranging about 111 mm. had yolked eggs 
measuring up to ‘24 mm. ; in one at 73 mm. they were ‘2 mm. 
On 26th May a female from the Dornoch Firth, 70 mm. in length, 
had eggs measuring ‘(09 mm. On 15th January a female of 144 mm. 
(52 inches) taken in 57 fathoms at the Dog Hole, off Aberdeen, was 
full of almost ripe eggs, and on 17th December several from Aberdeen 
Bay from 92 mm. to 106 mm. appeared to be spent. A female of 92 mm. 
was taken off the Cromarty Firth in December with nearly ripe eggs. 
From the above facts it appears that the spawning period of this species 
extends from the end of December to March or April. The occurrence 
of one with a few large fully mature eggs on Ist August was probably 
exceptional, and may have represented a late spawning, although the 
size of the fish is against that supposition. M‘Intosh has described the 
eggs as having been found deposited on Ist October, and some of them 
were kept alive until they hatched on 2nd March.* With regard to the 
size when they first reach maturity, it appears probable that the females 
become mature when under 80 mm. in length, and the males when 
under 70 mm. 
With respect to the rate of growth of the armed-bullhead the 
information in considerable. In the appended Table I have given the 
particulars of the measurements of certain lots, arranged in three-milli- 
metre groups, from which it will be seen that three annual series are 
usually represented. The smallest examples were got in October, 
November, and December, and the next smallest in spring. The first 
question to be decided is whether these forms got in autumn ‘and winter, 
varying from 47 and 49 mm. to 73 and 74 mm., are fish spawned at the 
preceding spawning season, 7.e. under or about one year old. M‘Intosh 
states that the larval and post-larval bullheads were not uncommon in 
St. Andrews Bay in April, measuring 7-8 mm., and that at the beginning 
of the month nearly ripe females were obtained. They were also got 
frequently in March, while in May they were abundant.t Specimens 
from 14 to 18 mm. were found from May to July; some in May were 
19 mm,; and others at the end of June and beginning of July 25 and 
and 26 mm. Specimens were procured by the “ Garland” in April up 
to10 mm. ‘Tosh gives the measurements of twenty-seven specimens of 
various sizes, and calculates that one in July, 17 mm. long, was about 
three months old ; three, 25 and 26 mm. on 4th and 5th July, to be 5 to 
54 months old; one on 24th February, measuring 46 mm., to be one year 
old, and others in May of 51 and 56 mm. to be fifteen months old; one 
in September, of 87 mm., to be one year and seven months old; one in 
December, 110 mm., to be one year and 103 months of age, and one of 
138 mm. in the same month to be two years and eight months old. 
In the push-net on the beach at Loch Fyne one of 27 mm. was taken 
on 3rd July, one of 34 mm. on 2nd July, and two of 41 and 52 mm. on 
28th September. 
On examining the Tables given below, it will be found that the first or 
youngest group in March is pretty well defined, and also the same group 
in August, and a calculation of the difference of the mean size indicates a 
growth in the period (of 139 days) of 27:2 mm, for the females and 26°3 
* Thirteenth Ann. Rep., Part I11., p. 231. 
+ Seventh Ann. Rep., Part I11., p. 271. 
Twelfth Ann. Rep., Part IL, p. 334. 
