of the Fishery Board for Scotland. 
345 
outline. The nuchal region and the mid-trunk are no less rotund, and 
project prominently from the yolk, while the dagger-shaped tail is stout 
and far less delicate and blade-like than in newly-hatched Gadoids (Plate 
XV. tig. 14). Perhaps the most striking external feature at this early stage 
is the great development of black pigment. It is aggregated upon the 
surface of the brain and spinal cord, and already forms a dense choroidal 
layer around the eyes. The post-branchial, hepatic, and intestinal areas 
are clothed so thickly that their form is wholly obscured when the embryo 
is viewed from the surface, while sections show that the large stellate 
corpuscles pass above and below the oesophagus, intrude into the inter- 
stices of the hepatic lobes, and form a dense layer around the renal tubules 
(Plate XV. fig. 9). A pigmented mesodermic extension (somatopleure) 
passes down the yolk from the trunk, and between that layer and the 
periblast pigment plentifully occurs, while that portion of the periblast 
whicli surrounds the oil-globule is thickly dotted with black spots. These 
spots, however, are confined solely to the surface of the periblast (Plate 
XV. fig. 1 3) and do not pass, as in the Gurnard, to the inner surface. This 
extraordinary development of chromatophores, which, it may be added, 
extend over the developing gill-arches, the otocysts, and the upper surface 
of the basis cranii, between the cartilage and the under surface of the 
brain, is only equalled by another feature, distinguishing Lopliius from 
other pelagic larvae, viz., the large development of serous or lymphatic 
spaces around the trunk. All young fishes exhibit in greater or less 
degree sub-epidermal spaces, and Mr E. W. Holt (4, p. 457) has recently 
described an embryo, apparently a species of Solea, which has a curious 
bladder-like expansion extending forward over the head, an exaggeration 
of the condition figured and described by Raffaele (6, Tav. 3, figs. 5 
and 6) ; but, if such examples be normal, they are far less remarkable than 
the larva of Lophius, the head and trunk of which is surrounded by 
enormous lymphatic chambers of a very interesting character. The 
membranous investment of the brain and spinal cord enclosps a spacious 
cavity, and the roof of the fourth ventricle especially forms a huge arched 
space (Plate XV. fig. 19), in great contrast to the condition in pelagic forms 
generally. Outside this membrane, which is pigmented, a second mem- 
brane occurs enclosing a space, y, which increases with the age of the 
larva (compare Plate XV. figs. 10 and 11 with, figs. 18 and 19), and in 
sections delicate strands traverse it, with many scattered cells. These 
strands are no doubt immersed in life in a colourless plasma. 
The sub-epidermal space proper (ss) occurs outside the second membrane, 
the chamber limited by which may be distinguished from the innermost 
medullary space as a perineural cavity. This outer chamber is pro- 
minent in all Teleostean embryos ; but in Lopliius it exhibits noteworthy 
features, and expands to a great size over the mid-brain and around the 
trunk to the tip of the tail. The tail in fish embryos is usually flattened 
laterally and blade-like, but the existence of a considerable perineural 
and of enlarged sub-epidermal spaces results in a rounded cylindrical caudal 
trunk; and the two ectodermal lamellae, which form the marginal membrane, 
approach each other only near the tip of the tail dorsally, and along the 
ventral (post-anal) border (Plate XV. fig. 14 em). 
Above the cerebellum, and posterior to the fourth ventricle, and again a 
little anterior to the root of the caudal trunk, aggregations of mesoderm 
cells make their appearance in the perineural space (Plate XV. fig. 9, or). In 
the embryo about to hatch, these cells form a considerable plate along the 
dorsal surface of the neurochord, and are so thickened in the median line 
as to resemble the lateral muscular plates. The median mass is indeed 
connected by strands of loose cells with the myotomes (Plate XV. figs. 9, 10), 
