DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 853 
No form hitherto examined shows this double frill so well, a feature probably connected 
with the peculiar condition of the ventral surface of the abdomen. In relation to the 
latter, we have immediately below the small and vertically elongated pectorals a spherical 
body, the liver, then a smaller mass (gut ?), and lastly the large ovoid swelling of the 
yolk, which is closely applied to the gut above and to the rectum behind. The latter is 
well marked, and appears to open by an anus at the tip. 
Unfortunately the preservation of this specimen was defective and the sections unsatis- 
factory, but one feature of note was observable, viz., the fact that the yolk contained a 
large oil-globule surrounded by a belt of protoplasm in which were a series of small 
oil-globules, which thus formed a ring round the larger central one. The lateral fold on 
each side of the yolk showed epiblast outside a core of intruding mesoblast. 
Certain features in this form approach those of the larval Arnoglossi, described by Dr 
RAFFAELE (125a, pp. 49-55). Zeugopterus, Rhombus lavis, and probably other Pleuro- 
nectids, however, also have an oil-globule in the egg. 
Ovum of Pleuronectid (B)—with large perivitelline space.—This large ovum, 
frequently met with in the trawling expeditions of 1884, and every year since, 
is characterised by its large perivitelline space, in which the yolk with the early blastoderm 
floats freely like a globule. At a later stage (PI. XIII. fig. 3) the yolk keeps the 
upper arch of the egg with the embryo curved beneath. The zona radiata is com- 
paratively thin, and it is sometimes difficult to obtain a clear view of the minute 
punctures (Pl. X. fig. 8). It is, however, not devoid of toughness. The contained 
embryo shows chrome-yellow and blackish chromatophores, the former extending nearly 
to the tip of the notochord. The newly hatched larval fish has been figured and described 
elsewhere,* so that it is only necessary to mention the later stages. The larval fish 
during the absorption of the yolk often shows prominent processes projecting from the 
surface of the yolk into the anterior space. When the yolk has been absorbed the fish 
presents three distinct yellowish bars behind the vent (Pl. XVIII. fig. 2), another at the 
latter (vent), and a line along the dorsum of the intestine, besides various touches of the 
same on the head and elsewhere. Stellate black pigment-corpuscles occur along with the 
yellow, and in the early condition are present over the yolk. ‘The eyes soon assume a 
silvery aspect. The larval fish is active and comparatively large, resembling in certain 
respects the plaice. It is probably a pleuronectid. 
Mr Cunnineuam describes the same egg before hatching.t It is not uncommon both 
in St Andrews Bay and in the open sea beyond. 
Unknown Ovum (C).—Besides the foregoing, a small undetermined ovum occurred in 
the mid-water net in April, and probably belongs to the same group (Pleuronectidz). 
The contained embryo is comparatively large and fills up the capsule almost completely. 
The larva issuing from this egg is represented in fig. 1, Pl. XVIII., the dull brownish- 
yellow pigment being characteristic. Moreover, the mouth of the embryo is open at the 
period of hatching—as in the plaice. 
* Vide Seventh Annual Report, Fishery Board for Scotland, 1889. + Op. cit., p. 105, pl. vii. fig. 2. 
