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 1 1 or 12 mm. on emerging. 

 The translucent body (PI. 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 (PI. 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 larvae is on edge (PI. 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 Cottus) is represented with a 

 small oil-globule behind the cardiac region. F. Kaffaele,* however, has quite 

 recently shown that certain Mediterranean forms, such as Mullus and Coris, have 

 pelagic larvae which bear the oil-globule at the tip of the prow-like yolk. The 

 feature is interesting, as this body in 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., LophiusJ frequenting like Anarrhichas the sea-bottom. When viewed from 

 above (PL XX. fig. 5), tbe 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. 



t It must be noted, however, that Lophius, unlike Anarrhichas, has a pelagic ovum (vide Agassiz " On the Young 

 Stages of Oss. Fishes," Proc. Amer. Acad. Arts and Sci., vol. xvii., 1882, pi. xvi. fig. 3). 



