224 Mr. E. Shann on the Life-history and 



goby 5*5 mm. long on June 9th might attain 17*2 mm. on 

 July 31st. These lines of growth, as they may be termed, 

 are seen to make a more acute angle with the base-line in the 

 region representing the winter mouths, which indicates a less 

 vigorous rate o£ growth than in the summer months. It may 

 be that there is a complete cessation of growth during mid- 

 winter, in which case the two extremities of the growth-line 

 between September and April would be more highly inclined, 

 and the complete cessation of growth indicated by a line 

 parallel to the base-line ; but of this there is no direct proof. 

 In order to prevent confusion the joining up of all the points 

 on the graph has been avoided, and a mean point between a 

 group of actual points has been preferred as a guide. For 

 the same reason, and because it is not probable the rate of 

 growth is constant for all specimens of G. minutus (even at 

 the same period of the year), some of these growth-lines, not 

 too widely separated, have been caused to converge and to 

 continue in the same line. The graphical method has the 

 further advantage of bringing out clearly the months in which 

 gobies of a certain length are most prevalent. 



From Table II., with its appended graph representing the 

 rate of growth of G. minutus in the Forth area, it seems that 

 these fishes neither grow so fast nor attain such a length as 

 their neighbours in St. Andrews Bay. The average rate of 

 growth per month for the summer period is about 3'5— 4'5 mm., 

 while that for the winter months scarcely exceeds 1*0 mm. 

 Both here and in the N.E. area a curious late brood of this 

 species of goby exists ; the young attain only 7*0 mm. at the 

 end of November in this case, and are probably equivalent to 

 those which reach 4"7 mm. in October in the Moray Firth. It 

 seems probable that the majority of larva? are hatched rather 

 later than in St. Andrews Bay, for numerous captures of 

 larvae are made in July and August. 



In the Clyde area a most interesting series of catches was 

 made in October, 1899, the results of which shed much light 

 upon the rate of growth of G. minutus in this area. One 

 batch was taken on the 7th of the month, the other three, at 

 different stations, on the 10th. It was evident at a glance 

 that each batch of these fishes could be divided, according to 

 the length, into two clearly defined groups. The length of 

 the larger fishes approached 60 mm., that of the smaller 

 35 mm. It seemed clear that the 35 mm. specimens were 

 the fishes of the current year, while the 60 mm. forms had 

 been hatched in 1898. Thus at a glance the approximate 

 growth of 6r. minutus in the Clyde area was obtained, i. e. 



