DEVELOPMENT AND LIFE-HISTORIES OF TELEOSTEAN FISHES. 875 
~ contents of the egg are finely granular. The usual changes take place, the nucleolus 
disappearing, and by and by, when the egg reaches 1 mm. in diameter, only coarsely 
granular contents are present. Before deposition the yolk clears up and the oil-globule 
becomes conspicuous. 
The earlier stages of the extra-ovarian development of the wolf-fish have not yet come 
under notice, for the ova procured on 16th January 1886 had reached an advanced stage, 
the embryos being considerably developed, and showing not only abundant pigment in 
the anterior dorsal region, and in the eyes, which had a silvery sheen, but an active vitel- 
line circulation. ‘The movements of the embryo within the egg-capsule, too, were frequent 
and vigorous. It was necessary to tear the large mass of adherent ova in order to place 
them in the glass vessels of the laboratory, and a few embryos were thus set free. 
During the next four or five days many spontaneously emerged, but the appearance of 
those which escaped on the 23rd or 24th of January presented no noteworthy advance 
on their predecessors. The larval fishes at this date measured 11 or 12 mm. on emerging. 
The translucent body (Pl. XX. fig. 2) is comparatively slender, and is surrounded by a 
delicate and continuous marginal fin. In the lanceolate caudal region a slight dilatation 
occurs. The yolk is bulky and of a translucent straw-yellow hue, and a large oil- 
globule of a dull yellowish tint is present. The coverings of the sac show finely granular 
cells with large nuclei (Pl. XXI. fig. 5). The pectoral fins are in constant motion, just 
as those of the young salmon are, and yet it is doubtful whether the young wolf-fishes 
here referred to did not escape prematurely. Some had difficulty in escaping from the 
zona radiata, a circumstance noted, however, at a much later stage, when the head and 
yolk-sac frequently remained enclosed, while the tail alone was free. 
The favourite position of the most vigorous larvee is on edge (Pl. XX. fig. 5), the 
rounded pendulous yolk resting on the bottom of the vessel, and thus steadying the 
young fish, while keeping its head above the sand or sandy-mud. The large oleaginous 
globule is situated on the anterior face of the yolk, a short distance below the head, and 
may possibly aid in maintaining the sac in the position just indicated. The situation of 
the globule is characteristic, for in no other British Teleostean has this precise position 
been noted, nor does AGassiz indicate it in any American form, though, in his conjoint 
work with WHITMAN, an unknown embryo (not unlike Cottws) is represented with a 
small oil-globule behind the cardiac region. F. RarrarELy,* however, has quite 
recently shown that certain Mediterranean forms, such as Mullus and Coris, have 
pelagic larvee which bear the oil-globule at the tip of the prow-like yolk. The 
feature is interesting, as this body im most forms in which it has been observed is 
situated towards the posterior border of the yolk-sac, as, for instance, in another form, 
viz., Lophius,t frequenting like Anarrhichas the sea-bottom. When viewed from 
above (Pl. XX. fig. 5), the globule projects just in front of the snout, the great vitelline 
* Abdruck aus den Mittheilungen aus d. Zool. Stat. Neapel., Bd. 8, Heft 1, pp. 20, 35, tav. 2, figs. 5, 6, and 
18, 1888. 
+ It must be noted, however, that Lophius, unlike Anarrhichas, has a pelagic ovum (vide Acassiz “On the Young 
Stages of Oss. Fishes,” Proc. Amer, Acad. Arts and Sci., vol. xvii., 1882, pl. xvi. fig. 3). 
