112 EATE OP GROWTH OP SOME SEA PISHES 



was exactly the same length. In the tank with it were several 

 vigorous flounders, and probably this was the reason that it had not 

 grown, the flounders having seized all the food put in the tank. 

 But numbers of this species, 6 to 7 inches in length, occur under 

 rocks, between tide-marks, in summer, which are obviously at the 

 commencement of their second year. This species reaches 18 in. 

 in length, and does not change colour when adult. My young 

 specimen, like the adult, is a dark rich brown on the sides, black on 

 the back, white on the ventral surface. 



Motella tricirrata, the Three-hearded BocTcling. 



On June 20th of the present year I went out for a fishing trip in 

 a mackerel boat, and when we got as far as the Mewstone it fell 

 dead calm, and remained so for some hours. The surface of the 

 sea was covered with great quantities of Noctiluca miliaris, here and 

 there collected in patches and streaks into a thick scum of a salmon- 

 pink colour. Darting about at the surface were numerous small 

 active fishes, of which I secured a great number, and found on ex- 

 amining them ashore that they were the young of Motella tricirrata, 

 the three-bearded rockling. These young fish were swimming at 

 the very surface of the water, causing it to ripple by their motion. 

 Fishermen at Plymouth call all such young fish '' britt," not distin- 

 guishing one species from another. The older naturalists described 

 this young form as a distinct species, and Couch calls it the mack- 

 erel-midge. 



Among my specimens there are three stages to be distinguished, 

 which pass gradually into one another. The oldest stage is from 

 2*5 to 3*2 cm. long (1 to 1-3 inch), and is closely similar to the 

 adult, except that the sides are brilliantly silvery, which is not the 

 case in the adult. In this stage the fins are all similar to those of 

 the adult, the pelvic reaching only half way to the anus. The 

 youngest stage is under 1 cm. in length, and the skin is almost 

 transparent, the silvery opacity commencing to develop in the 

 largest specimens. There are pigment cells, especially on the back. 

 The fin-rays have only recently begun to develop and are not com- 

 plete at their distal ends ; the anterior dorsal fin is not visible, but 

 the principal peculiarity is the pelvic fins, which are comparatively 

 long, extending beyond the anus, and having a dense black colour 

 over their outer halves. The second stage is intermediate between 

 these in all respects : it is from 1 to 2'5 cm. in length, and in the 

 different specimens in this stage can be traced the development of 

 the silvery layer in the skin, and of the anterior dorsal fin, and the 

 gradual reduction of the pelvic fin. A specimen of the young 



