Rate of Growth in Gobius minutus. 225 



35 mm. the first four months and 25 mm. in the next twelve. 

 It is hard to reconcile this conclusion with that formed 

 from observation of the gobies of St. Andrews Bay. The 

 rate of growth during the first four months is far more rapid 

 in the Clyde forms, viz. 8'4 mm. per month as compared with 

 5*3 (rarely more) on the ea-^t. On the contrary, the average 

 growth per month during the succeeding year is very much 

 more slow in the Clyde forms. The most probable explana- 

 tion of the latter phenomenon is that in the west coast gobies 

 there is a true winter rest, accompanied by cessation from 

 growth. This supposition has been illustrated graphically in 

 the appendix to Table IIF. In this case the lines connect the 

 points representing fishes caught at the same time; the pjints 

 representing catches of fishes averaging 6'0 mm. and 54 nun. 

 respectively only happen by chance to fall on one of the 

 imaginary growth-lines, for they were added after these had 

 been drawn. Other catches described in Table III. are also 

 represented on the graph. The natural conclusion, from the 

 da! a so far cited, is that the Clyde specimens of G. minutus, 

 if not a distinct variety of the species, are at least a race 

 which has a markedly different rate of growth at various 

 periods of the year from that found on the east coast. It 

 might be supposed that this western race seldom or never 

 exceeded 60 mm. ; but two specimens from Millport reach 

 67 and 70 mm. respectively. As the date of capture of the 

 latter is not known, they have not been entered in Table III. 



The rate of growth in the N.E. area agrees well with that 

 deduced for St. Andrews Bay. The rate of growth per 

 month during the first summer is slightly over 5 mm. 

 Moi cover growth seems to continue pretty vigorously during 

 the winter months, for one specimen measuring 60 mm., 

 probably from an early brood of the preceding year, was 

 captured off Aberdeen in the middle of May. The appended 

 graph agrees, too, with that illustrative of the forms of 

 St. Andrews Bay, the lines of growth becoming slightly less 

 inclined in the area representing the winter months. The 

 rate of growth during the winter averages about 3 mm. per 

 month. The range in size of fishes taken in October in this 

 area is remarkable, the smallest being but 4*7 mm., while the 

 largest is 36'0 mm. in length. 



Four specimens of G. minutus were taken on 20/1/06 in 

 the river Tay, four miles above the bridge. These measured 

 67, 65, 63, and 49 mm. respectively, and their age was 

 probably about 20 months, though the smallest specimen may 

 have been somewhat younger. Whether these forms would 



