DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 789 



effected. There is, at an early stage, no true dermis beneath the Malpighian layer. 

 Pouchet speaks of this subepidermal tissue as a soft variety of laminated tissue, having 

 a very loose texture, and therefore little firmness (No. 119, p. 291), but in its earliest con- 

 dition it is simply a soft semifluid stratum in which amorphous matter abundantly occurs. 

 In this layer pigment develops (pt, PL IV. figs. 13, 20), and always appears as definite 

 amorphous corpuscles, not a mere diffused solution. 



In different species the early coloration shows very distinctive features, the colour of 

 the pigment and its distribution being, in fact, so striking as to afford aid in diagnosis. 



In some species the pigment is confined to the embryonic trunk (PL V. fig. 2) ; in 

 others it extends over the extra-embryonic layer, i.e., the yolk-sac (PL XVI. figs. 2, 8). 

 Certain forms, again, exhibit one kind of pigment (PL XVII. fig. 1; PL XIX. fig. 8) ; others 

 show two or more colours in the larval stages (PL XVI. figs. 1, 3, 5-9). No generalisation 

 can be made, for in the same genus closely allied species show great diversity in these 

 respects. Usually the pigment occurs in the form of minute isolated spots scattered 

 upon the dorsum, and visible within one or two days after the closure of the blastopore ; 

 though it frequently forms superficial protuberances, evidently pushing out the epi- 

 dermal stratum at certain points. The form of the corpuscles undergoes rapid changes ; 

 thus in a larval cod under examination two spots at the anterior border of the liver were 

 seen to be finely branched, but before a sketch could be completed they visibly altered, 

 and presented a simple rounded aspect. 



In the cod (PL XIX. fig. 8) and haddock (PL XVII. fig. 1) black spots only occur. In 

 the ova of the former species, seven days after fertilisation, these spots, amorphous or 

 rounded in form, were scattered sparsely over the dorsum and lateral regions, but in a 

 few days they multiplied and extended from the snout to the tip of the tail, without any 

 regular disposition. In larvae of the cod, soon after emerging, however, a further change 

 in the distribution of the pigment takes place, for the spots, which are now elaborately 

 stellate, become aggregated in four distinct bands (PL XIX. fig. 8), two very dense 

 broad bands — a pectoral and an abdominal — occurring on the trunk proper ; while 

 the tail exhibits two less dense bands, and often indications of a third. The haddock 

 never shows this regular series of dark bands, which seem to be so characteristic in the 

 newly emerged cod. In the ova of the haddock on the eighth day (two days after 

 closure of the blastopore), black spots are irregularly dotted over the dorso-lateral 

 regions, and subsequent changes chiefly affect the number and form of the spots. A 

 larva two days after emerging shows stellate spots of the most elaborate form, which 

 send out complex ramifying processes. These spots appear on the cranial region, and 

 very thickly in the post-otocystic and lateral regions of the trunk proper. Posteriorly 

 they are chiefly confined to the lower half of the caudal trunk, only two or three large 

 spots occurring above the level of the notochord. Occasionally one or two spots are 

 seen to send processes into the fin-membrane. The whiting offers a great contrast to the 

 foregoing Gadoids, since on the eighth day (three days after the closure of the blastopore) 

 very faint yellow spots appear, and are thickly distributed over the entire trunk, including 



