6 J. T. CUNNINGHAM. 
the diameter of the ovum. - The above description, founded on 
my own observations, agrees very closely with the account 
given of the cod’s ovum by Professor John A. Ryder. 
The ovum of Trigla gurnardus is distinguished by the 
presence of a single large oil-globule, of brownish-yellow colour, 
which is situated between the surface of the yolk and the peri- 
vitelline membrane. The most surprising fact about this oil- 
globule is that it is capable of free motion in the perivitelline 
space. When the egg is rotated on a slide the oil-globule 
rapidly rises to the highest pole in whatever position the egg 
is placed. It does this even when the segmenting blastodisc 
is placed uppermost, passing between the blastodisc and the 
vitelline membrane. Whether the oil-globule is at a later 
stage enveloped by the blastoderm I am not able to say. I am 
not aware that a moveable oil-globule has been described in any 
Teleostean ovum before, and I cannot say at present whether 
the peculiarity is confined to the eggs of the gurnard or not. 
The larve of the whiting and haddock when hatched are in 
a condition similar to that of the newly-hatched cod as 
described by Ryder. The intestine ends immediately behind 
the yolk, and if it is open at all does not open at the edge of 
the ventral median fin; the terminal portion of the intestine 
reaches only half way down the breadth of that fin. There are 
no red blood-corpuscles, but the eyes are pigmented, and there 
are scattered stellate pigment-cells on the back and sides. The 
mouth is not formed, but the gill-slits are opened. The yolk 
is still of considerable size, and by its buoyancy causes the 
young fish to be suspended in the water back downwards. 
Part II.—EmBryo.oGIcat. 
Some time after fertilisation in a Teleostean a furrow is 
formed across the blastodisc (fig. 1), which is at first super- 
ficial, but is soon continued by a plane of division to the lower 
limit of the disc. At right angles to the first a second furrow | 
and plane of division are next formed, so that the blastodisc is 
divided into four equal and similar parts, in each of which 
