of the Fishery Board for Scotland. 



231 



The variation in length when the eye is half-way is, therefore, for the 



Dr. Ehrenbaum"*^ gives this variation for the plaice as 13 to 14-5mm. for 

 living specimens. Mr Dannevigf places this stage at 12 •4mm. for living 

 specimens. If from 1 to 2mm. be allowed for contraction in spirit — 

 measurements were made to find this contraction and gave this result for 

 specimens about this length — then my results agree partly with Ehren- 

 baum's, viz., from 11*5 to 14*5mm. The maximum was 12mm., which, 

 allowing for contraction, becomes about 13mm. for living specimens, 

 somewhat greater than the length given by Dannevig. Artificial and 

 uniform conditions perhaps account for this last result. Dannevig does 

 not mention any variations in length. 



Measurements were also made of the breadths at this stage : — 



Only one specimen of the dab 16'5mm. in length reached 5mm. ; 

 4*5mm. was the greatest breadth for the others. The average for the 

 dab was 3'8mm. ; for the plaice 4'3mm. Dannevig gives 4'8mm. for 

 living specimens of plaice. Lengths were measured from tip of snout to 

 end of caudal fin-rays; breadths, across broadest part of body, excluding 

 the median fins. 



The determination of the lengths and breadths at complete meta- 

 morphosis is the next point to be considered. Some specimens 

 below 11mm. were found with metamorphosis nearly complete — 

 metamorphosis being considered complete W'hen the dorsal fin was at 

 least .halfway along the border of the left eye, but these specimens were 

 evidently much contracted. On the other hand, there were specimens at 

 14"5mm. with metamorphosis barely complete. These specimens were 

 considered to be plaice from their great breadth. 



The variation in spirit specimens is, therefore, from 12 to 15mm. 

 For living specimens this would be from 13 to 16mm. 



Specimens were collected from the rock-pools and the harbour during 

 the months of May and June. The smallest completely metamorphosed 

 was 14mm., and the largest incompletely metamorphosed was 15"5mm. 

 From 14 to 16mm. would, therefore, represent the variation in the 

 specimens during the past year, 1897, but 13mm. represents better the 

 lower limit for former years. Ehrenbaum would make this variation 

 from a little under 14mm. to 18mm. For spirit specimens the average 

 length is between 13 and 13'5mm., which, for living specimens, means 

 over 14mm. Dannevig gives 13*7 6mm. as representing the length of 

 the specimens reared artificially. 



The breadth of the plaice when metamorphosis is just complete is 

 from 5 to 6mm.; none with breadth below 4*8mm. were found with 

 metamorphosis complete. On the other hand, several with breadth 

 5*5mm. were incompletely metamorphosed. Dannevig gives 6'4mm. for 

 living specimens. To ascertain the limits of complete metamorphosis of 

 the dab one must reason from the spirit specimens. The smallest almost 

 complete is 15*25mm. ; another in exactly the same phase is 18mm. 

 Two specimens at 17mm. andl8mm. have completed metamorphosis. 

 A number of specimens at 16mm. are incomplete, and in one, 16'5mm., 

 the eye is only half-way. The limits in spirit are therefore 15 '5 mm. 

 to 18mm., and, in the living condition, from 16 to 19mm. probably. 



* Loc. cit., p. 265. 

 t Loc. cit, p. 187. 



Dab. 

 13'5 to 16*5 mm. 



Plaice. 

 10 to 13-5 mm. 



For the Dab. 

 3 to 5 mm. 



Plaice. 

 3 to 5*5 mm. 



