of the Fishery Board for Scotlcmd. 
291 
in this instance easily followed. The free condition of the oii-globule in 
these instances was probably abnormal, but it is worthy of note. Five 
conspicuous black patches or bars further distinguish the larva, viz., one 
on the head and four on the body. The chromatophores on the head are 
somewhat irregularly scattered, though the front view of the head in ovo 
(PI. XV. fig. 11) shows that a more or less symmetrical series occur over 
each eye. The first patch or bar on the trunk is placed rather behind the 
middle of the yolk, though a little variation exists, and it is rendered the 
more conspicuous as the black pigment of the sub-notochordal region 
is present beneath (PI. XV. figs. 12-14). The chromatophores in 
these areas are very finely ramose. The next patch or bar lies on the 
muscle-plates behind the vent, the last is at the top of the tail, while a 
less definite one is intermediate. As already mentioned, a slightly 
yellowish hue (greenish by transmitted light) pervades the head, yolk-sac, 
and the tip of the tail. No sign of the cutaneous process in front of the 
otocyst is now visible, so that it may have been idiosyncratic. The 
rectum is high up on the marginal fin, but the lumen is visible just within 
the tip. The urinary vesicle is distinct. The notochord is multico- 
lumnar. The surface of the yolk-sac, the pectorals, and the marginal fins 
are minutely vesicular. A little black pigment appears in the eye. The 
healthy larvae are active. 
Next day (31st May) the chief feature was the increase of the greenish- 
yellow hue on the under surface of the head, on the yolk-sac, and the tip 
of the tail, this tinge being due to the development of the cutaneous 
vesicles formerly mentioned, and it makes a bold contrast with the pinkish 
oil-globule. The ramifications of the black chromatophores have every- 
where increased, those at the tip of the tail having a radiate arrange- 
ment like fin-raj^s. The liver appears on the ventral border of the gut. 
The rectum has moved downwards a little, and often contains a rounded 
mass. The pectorals and otocysts are larger. A peculiar abnormality 
occurred in an example (PI. XVI. fig. 19), viz., the presence of a long 
narrow process (a) resembling a diverticulum in the rectum, which in this 
instance had reached the somewhat defective border of the fin. 
The changes which were visible on the 1st June consisted of the pro- 
jection of the cartilages of the mandible, the increase of pigment in the 
eyes, and the passage of the rectum, with the urinary vesicle, near the 
fin-margin (PI. XV. fig. 13 and PI. XVT. fig. 13). The little fishes are 
restless, and the use of the pectorals in balancing is more pronounced. 
The yolk has considerably diminished. Next day the eyes showed a 
greenish silvery lustre, and peristaltic movements of the gut were marked. 
Moreover, though the mouth is still closed, spasmodic movements of the 
mandibular region occur. As in the cod, rockling, and other forms, the 
black chromatophores, when placed against a dark background under a 
lens, look brownish. 
On the 3rd the larva were characterised by their activity, and especi- 
ally by the rapid vibrations of the pectorals. The yolk has now greatly 
diminished, only a small anterior portion (PI. XV. fig. 13) now remain- 
ing, while the reddish-brown oil-globule has been drawn forward and 
almost concealed under the greatly increased black pigment of the upper 
region of the abdomen. 
The larvae on 6th June, that is about a week after hatching (PI. XV. 
fig. 14), swam more readily, and the mouth had opened, the mandible being 
moved up and down with the hyoidean apparatus. Only a trace of the 
oil-globule remained, and the yolk was almost absorbed. The rectum 
had not yet reached the border of the marginal fin, but it was close to it, 
and its margin was slightly papillose. Little change had taken place in 
