76 



Fart HI. — Twenty -first Annual Report 



In males of 109, 99, 96 mm. the testes were small and solid. 



On 2-4th 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. 

 (5| inches) taken in 57 fathoms at the Dog Hole, off Aberdeen, was 

 full of almost ripe eggs, and on 17 th 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 1st 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 1st 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 whethei- 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, i.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.f 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 procui ed by the " Garland " in April up 

 to 10 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 

 5| 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 rnm,, to be one year and seven months old ; one in 

 December, 110 mm., to be one year and lOg months of age, and one of 

 138 mm. in the same month to be two years and eight months old.q: 



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 gi-oup in March is pretty well defined, and also the same group 

 in August, and a calculation of the diflference 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 III., p. 231. 

 t Seventh Ann. Refi., Part III., p. 271. 

 Tu-e/fth Ann. Rep., Part III., p. 334. 



