DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 791 
The dab (Pleuronectes limanda) has a distribution of pigment similar to that in the 
flounder, though the yellow spots seem to take a more distinctive linear disposition, two 
lines running along each side of the embryo, the upper line marking the dorso-lateral limits 
of the neurochord (PI. V. fig. 11). This distribution is well seen when the embryo is viewed 
from above. Pigment (yellow) appears when about thirty protovertebra are outlined 
(i.e., about the seventh day after fertilisation). On the fourteenth day (two days after 
emerging) the pigment-spots around the margin of the eyes and the otocysts coalesce to 
form larger patches, irregular in form. A few days later, the upper lobe of the caudal 
membrane is diversified by the development of an undulating line of yellow pigment, or 
rather of a linear series of crescentic patches. Other spots occur thickly in the anal region, 
but the yellow pigment of the trunk is confined for the most part to two lines, as above 
described (Pl. XVI. fig. 6). In a more advanced embryo, thirteen days after extrusion, 
the crescentic series of patches in the caudal fin is still more boldly marked, while two or 
three irregular touches appear on its lower lobe. The stellate pigment-spots are now 
meagre, occurring, as in the earlier stage just described, over the eyes, along the ventral 
region, over the greatly diminished yolk-sac, and very sparsely on the tail. The eyes 
have become darker, by increase of their black choroidal pigment, and about this time 
they show a striking green lustre in oblique light (Pl. XVI. fig. 3). 
In the plaice (Pl. V. fig. 6) black pigment-spots, mingled with finely stellate 
bright canary-yellow corpuscles, develop, though comparatively late, and when the embryo 
is freed it does not show the marked pigmentation of the cod or like forms. On the 
third or fourth day after emerging yellow pigment appears as very minute amorphous 
spots. In Pl. XVI. fig. 5, the peculiar distribution of the two tints is seen. The head 
and trunk present very minute, scattered spots. The ventral margin of the alimentary 
tract shows stellate black spots ; while the upper and lower contours of the caudal region 
have bold lines of stellate spots, which extend to the caudal fin-membrane, though con- 
fined to the lower lobe, and here the spots are simple and very minute. The yellow 
pigment appears only as a narrow area towards the end of the tail, viz., the upper 
margin of the posterior half of the caudal trunk. At the root of the tail a dense patch 
of black spots occurs, extending obliquely just above the urinary vesicle. 
Pigment appears in the gurnard at a slightly later stage than in the foregoing forms, 
It consists of very pale yellow spots, which have a delicate sea-green tinge in certain 
lights. They are sparsely scattered over the trunk proper, but form a rude line along 
the dorsum, and an undulating line along the sides and around the eyes. Three or four 
days later minute black spots occur, and both colours are sparsely distributed over the 
yolk-sac, and around the large oil-globule. A more advanced embryo is seen in Pl. XVI. 
fig. 8, at which stage irregular patches of yellow and black pigment exist upon the 
dorsal and ventral portions of the caudal membrane. The spots send out branched 
ramifying processes, and the pectoral fin exhibits distally a radial yellow and black 
coloration. The eyes, however, are very slightly tinted with minute black spots. In 
still later larval and post-larval stages the pigment diminishes, and only occurs very 
