176 



Part III. — Twenty-second Annual Report 



It is clear, however, from the measurements that at least three annual 

 series or groups of sprats exist in these collections, although they are rarely- 

 well represented together in any one collection, and this is obvious from 

 the curves in the plates, and especially from the curve for the combined 

 measurements in December (fig. 10, PL IX). 



The first or early series has been already alluded to, and the facts show 

 that the sprat grows slowly. 



Three collections were made in which spawning sprats were got, one 

 on the 1st April, off Burghead, one on the 1st June in the Cromarty 

 Firth, and the third on 31st March in the Dornoch Firth. In the first 

 named collection the seventy-two sprats forming the second series 

 measured, as stated, from 108 to 126mm., with an average of 118* 1mm. 

 The initial sizes were as follows :— one at 101mm., one at 104mm., one 

 at 108mm., and then the series was continuous from 110mm. onwards. 

 Unfortunately, the condition of the reproductive organ was not examined 

 throughout the whole series, but in eighteen males from 104mm. to 

 125mm. the testes were large and apparently ripe or approaching 

 ripeness ; they were examined after preservation in formaline solution. 

 The number of female sprats examined was nineteen, varying in size from 

 110 to 126 mm., and they all contained either fully mature eggs or eggs 

 approaching maturity. In those fully mature the germinal vesicle had 

 disappeared and the yolk was translucent but still somewhat granular. 

 It was noticed that there was not any indicatiou of an external swelling 

 of the belly such as is found as a rule in fishes with fully-developed 

 reproductive organs, so that it was impossible to tell from the external 

 examination whether the fishes were about to spawn or not. The 

 number of the mature or nearly mature eggs was, moreover, very small 

 compared with the number to be found in the ovaries of most other fishes 

 with pelagic eggs — amounting only to a few thousands [see p. 285). I 

 append a Table giving particulars of the weights (in grammes) and 

 condition of the reproductive organs in some of those examined : — 



Males. 



Size. 



Weight, 



Weight of 

 Testes. 



Females. 



Size. 



Weight. 



Weight of 

 Ovaries. 



Condition of Eggs. 



119 

 121 

 115 

 120 

 123 

 124 

 116 

 119 

 117 

 114 

 114 

 113 

 104 



10- 8 



12- 2 

 9-1 



11- 5 



13- 5 

 13 

 107 

 11-8 



8-8 

 10-5 



8- 3 



9- 5 

 6-5 



07 



0-7 



0-5 



0-56 



0-75 



0-58 



0-52 



068 



0-3 



0-56 



0-2 



0-56 



0-30 



122 

 120 

 124 

 122 

 126 

 122 

 121 

 117 

 118 

 120 

 118 

 111 

 110 



12-8 

 12-0 



12- 8 

 10-5 



13- 0 



10- 7 

 12-0 



11- 0 



10- 7 



11- 8 

 11-7 



0-38 



0-492 



0-44 



049 



0-42 



0-33 



0-29 



0-34 



0-20 



0-54 



0-32 



0-22 



Largest yolked up to *46 mm. 



•44 „ 

 •44 „ 

 •609 „ 

 •42 „ 

 •38 „ 

 •44 „ 

 •44 „ 

 •336 „ 

 •651 

 •378 „ 

 •336 „ 



