St. Andrews Marine Laboratory. 301 



third partiallj. Four specks of white are placed along the 

 ventral margin, two lying in the basal line of the anal fin. 

 A few minute specks occupy the space between the latter and 

 the larger upper series. Large silvery patches, again, extend 

 from beneath the eye to the end of the abdomen. A few 

 brown specks appear on the ventral surface in front of the 

 pelvic fins, and two boldly marked brown touches lie in the 

 median line between the latter and the anus. 



Besides the white touches which enliven the dorsal fin 

 an opaque brownish one occurs in front. The soft rays of 

 this fin have not yet attained the proportionally elongated con- 

 dition of the adult organ. The pectorals are large and 

 somewhat transparent, their very rapid vibratory movement 

 resembling that of Hippocampus and the Syngnathidse. 

 A brown bar, however, marks their fleshy basal region, 

 which in these and many other post-larval fishes is much 

 larger in proportion than in the adult — a condition pro- 

 bably connected with increased functional activity. The 

 ventral fins are opaque white, with a brownish belt in front 

 (anterior rays) ; this belt, moreover, joining a brown band 

 which proceeds upward to the base of the pectorals, where 

 it bends nearly at a right angle straight backward to the 

 posterior part of the abdominal wall. The anal fin has a 

 brown patch (covering two rays) in front. None of the blue, 

 yellow, or orange, so common in the adult, had yet appeared. 



After immersion in spirit only the dark pigment remains, 

 and thus the body has a peculiarly blotched or speckled 

 appearance posteriorly, while the head and abdomen are 

 striped. 



The colour of the ventral fins in the post-larval forms of 

 diverse families of fishes is apparently a feature of moment. 

 Thus the post-larval Motella has its enormous white ven- 

 trals tipped with black, as Alex. Agassiz clearly describes 

 and figures. The young cod, haddock^ and whiting have 

 pure white ventrals terminated by a long whip-like process 

 at the end of the second anterior (or outer) ray. The great 

 ventrals of the post-larval ling are conspicuously tinted of an 

 ochre-yellow. The colour of the huge ventrals of the 

 fishing-frog is not mentioned by Giinther or Agassiz, but it 

 is not unlikely that the post-larval pigment in this form also 

 is peculiar. The pelagic habits of many fishes at this stage 

 are probably associated with these peculiar tints, just as both 

 sides of most post-larval Pleuronectidse are tinted for a time, 

 as the ventral surface of the large abdomen of Gallionymus 

 at this stage is of a dusky blackish hue, and as the abdomen 

 in certain post- larval Colti is furnished with a broad and 

 conspicuous belt of black. 



Ann. & Mag. N. Hist. Ser. 5. Vol. xx. 21 



