26 A. E. HEFFORD. 



Zeiigopterus norvcgicus, Coll. Norwegian Top-knot. 



The oil-globule is commonly pale green and the yolk-sac slightly 

 rugose. Before the outgrowth of the caudal rudiment the periblastic 

 pellicle of the oil-globule becomes visible, and fine black chromato- 

 phores appear on the embryo and yolk-sac. They are very closely set 

 on the former but less dense and mostly stellate in form on the latter. 

 Over the whole embryo and yolk-sac there is a pale greenish yellow 

 tint, but no separated, coloured chromatophores are visible as yet. 

 Yellow pigment cells soon appear on the embryo and yolk-sac, and by 

 the end of embryonic life they become conspicuously predominant. 

 The black chromatophores show dense, rounded centres, from which 

 fine ramifications proceed. Some of tlie few yellow chromatophores 

 on the yolk-sac are stellate, with no specially large centre. On the 

 trunk of the embryo, just before hatching, they are large and of vague 

 outline, and so close together as to give the ef!ect of a diffuse tinting 

 along the whole length of the body, except the extreme caudal end. 

 Black pigment is fairly uniformly distributed over the body, but shows 

 some concentration into dorsal and ventral lines. A newly hatched 

 larva measures 258 mm., with a pre-anal length of 1"16 mm. The 

 snout projects conspicuously forward over the yolk-sac, and the anus 

 is situated some little distance behind the posterior end. Ehrenbaum 

 {oi?. cit.) describes the position of the oil-globule as usually at the 

 middle of the ventral side of the yolk, but I have generally found it post- 

 median. The pectoral fins are well developed. The pigmentation is 

 extremely rich. A difluse yellow effect, which is evident to the naked 

 eye, is produced by the close proximity of the large chromatophores 

 (greenish yellow by retiected light), which are distributed over the body, 

 fins, and yolk-sac, most densely along the dorsal and ventral contours 

 and the upper and lower margins of the unpaired fins. Black chro- 

 matophores are more aljundant, but smaller and much less conspicuous. 

 A very characteristic feature is the stopping short of the pigmentation 

 of the unpaired fins some little distance from the caudal extremity, 

 so that this part of the larval tail is quite clear. The same arrest of 

 yellow chromatophores is seen on the body itself, but small black 

 pigment spots occur as far as the posterior extremity. A further 

 conspicuous character of this species is the regular, fringe-like arrange- 

 ment of both the black and yellow pigment along the outer margin of 

 the unpaired fin, in the early stages of the larval development. The 

 fringe-like effect is accentuated by the finely pectinate form of the 

 chromatophores in this region. With the absorption of the yolk 

 the intensity of the yellow pigment increases, although undergoing 



