of the Fishery Board for Scotland. 
321 
The egg appears to develop slowly, though this was probably due, 
in some respects, to the severity of the weather in March. Black 
pigment very early occurs in the embryo, forming a lino of chromato- 
phores on each side of the body anteriorly. The centre of the heart 
is granular or papillose, and the skin, before hatching, is minutely 
vesicular. 
On extrusion (PI. XII. figs. 5 and 6) the larva floats with the ventral 
surface uppermost, and the oil-globule is at the posterior and inferior 
part of the yolk. Moreover, it has several blackish chromatophores. 
One of the most marked features is the motionless condition of the 
heart, faint contractions only occurring at distant intervals on the second 
or third day. It is possible that such may take place at intervals earlier 
if observation had been prolonged enough ; but, at any rate, it presents a 
contrast to the condition in other forms in which the heart usually 
pulsates actively before they leave the egg. In an example of the 
fourth day, the contractions begin at the venous end, which is directed 
forward, and slightly to the left, or when viewed from below, slightly 
to the right. The blackish chromatophores form a broad lateral bar in 
front of the tail, and a small group somewhat anterior, and those on the 
head and sides behind the yolk-sac are better developed. Under a lens 
(with refracted light) the pigment has a blackish-brown aspect. The 
alimentary canal is in a very rudimentary state, and ends blindly in the 
cutaneous tissues above the oil-globule and behind the yolk. The ventral 
marginal fin extends forward on the yolk, forming a crest as far down- 
wards as the oil-globule. 
In a day or two the lumen of the alimentary canal extends from the 
otocysts backward, but no anal opening can yet be observed. The yolk 
is still curiously streaked and wavy, and the cutaneous tissues are 
cellular, a streaked arrangement occurring in the tail. Two distinct 
pigment-bars exist behind the yolk-sac as in Motella (PI. X. fig. 7), 
but the posterior is much the larger as well as the earlier developed. 
A chromatophore or two also by and by appear ventrally near the tip of 
the tail. The chromatophores are numerous on the head and sides of 
the body as far back as the posterior border of the yolk-sac. 
In its earlier stage the larva is more or less quiescent — floating near 
the surface of the vessel, and only gyrating occasionally. As it gets 
older it now and then darts actively about, such movements, apparently, 
stimulating the heart into action. 
A similar egg appears in the collections of the 'Garland' in the 
Forth, and may be connected with a Motella^ e.g.^ M. tricirmta. 
4. On a Second Unknown Egg, and Larva with the Oil-Globule 
AT THE Ventral Border of the Yolk. 
Towards the middle and end of May and onward into June an egg 
not infrequently occurs in the bottom tow-nets which seems to be closely 
allied to that figured in the Researches, in fig. 4, PI. V., but which is 
not specially described in that treatise. It is larger than the foregoing 
(that supposed to be connected with Motella iricirrata), measuring about 
•039 in. or "9906 mm. in diameter (PI. XIII. fig. 4). During develop- 
ment yellowish pigment appears on the body of the embryo and the 
surface of the yolk-sac. 
On extrusion the larva is readily distinguished by the fact that the 
oil-globule, which is comparatively small, is placed considerably in front 
of the posterior border of the yolk-sac, as shown in the lateral view 
of an older stage in the Researches, PI. XVII., fig. 4. Moreover, the 
X 
