344 
Part IIL-^Ninth Annual Report 
A few of the ova in the portions of the egg-band examined were found 
to be abnormal and had undergone no embryonic development, the 
periblast forming merely a corrugated pellicle around the large yolk-globe. 
Most of the eggs exhibited the embryo in a somewhat advanced condition, 
and apparently ready to emerge. The young fish, with its appended yolk, 
completely fills the cavity of the egg-capsule, which is so pressed upon by 
adjacent ova that the spheroidal form is lost, and in optical section a 
pentagonal outline results (Plate XIV. fig. 1). Agassiz and Whitman 
speak of a large perivitelline space in which the embryo moves freely, 
and Agassiz figures this condition (1, Plate XVI. fig. 2), and shows the 
capsules of adjacent eggs as forming thickened septa.* In the Dunbar 
specimens the perivitelline space was small and the opposed capsules of 
the ova formed very thin membranous septa, a condition difi'ering greatly 
from the American specimens, though, no doubt, reagents and immersion 
in alcohol had produced much alteration. 
The points of difference are however so numerous, both in the ovum 
and the embryos immediately after hatching, that the descriptions of the 
American LopJiiiis will, in many respects, not apply to the Scottish 
specimens. The " fifth day " stage evidently corresponds to Agassiz's figure 
"a few days after hatching" (1, Plate XVI. fig. 5), though the rod-like 
ventral fins are much higher in position than in the American example, 
while the latest or post-larval stages figured by Agassiz bear little or no 
resemblance to the valuable post-larval Lophius obtained by Professor 
M'Intosh in 1886 (3, Plate XIX. fig. 6, p. 869), a unique specimen barely 
7 mm. in length. 
The earliest stage studied at St Andrews (Plate XIV. fig. 5) exhibited 
the features of an advanced embryo, and appeared to be ready to emerge 
from the egg. As compared with Gadoid or Glupeoid embryos, it is 
stout and stunted, the head large and obtuse, the trunk short, and the 
thick dagger-shaped tail only partially encircles the yolk. The last- 
mentioned is large and globular, and a flattened oil-globule lies on 
its posterior side, enveloped in a thick coat of protoplasm, richly 
pigmented. The globule does not indent the yolk in the specimens studied, 
but lies compressed as a flattened disc of oily matter upon the surface of 
the bulky vitellus. It forms a dark mass on account of the numerous 
stellate spots of black pigment covering the surface of its protoplasmic 
envelope. The yolk at the time of hatching (Plate XIV. fig. 2) has so 
diminished as to leave a large area between its surface and the integument. 
This large interspace is divided by the mesodermic extension of the 
parietal walls of the abdomen — the cavity enclosed by this thin layer of 
mesoderm being really continuous with the coeloma, while the equally 
spacious cavity outside is the sub-epidermal space, forming part of a 
system of enormous sub-epidermal spaces, which are strikingly prominent 
in the larval Lophius (Plate XV. figs. 10, 11, and 12, ss). Pelagic embryos, 
as typified in the Gadoids and Pleuronectids, are usually characterised 
by their delicate attenuated form, translucency with slight pigmentation, 
and by the oval shape of the yolk. Lophius, however, even before extru- 
sion, presents very different features, and recalls rather the clumsy and 
deeply tinted larvae of Amphibians, or the robust embryos of Teleosteans 
with demersal ova and a rich vitelline circulation. Thus the brain is in 
an advanced condition, the enormous optic lobes being pushed forward 
upon th.3 fore-brain, and imparting to the head its characteristic blunt 
* Isolated eggs of Lophius are said to occur, and such a free egg is figured in the 
paper already referred to (2, Plate VI. fig. 1). This egg is nearly spherical and the 
translucent capsule is very thin. An account of the number of ova produced by this 
species will be found at p. 251. 
