THE EGG AND DEVELOPMENT OF THE CONGER EEL. 
3V) 
length which the larva can attain in a given species, and the amount of diminution which accompanies 
metamorphosis, there are great individual variations. 
Grassi assumes that three vertebrae develop to correspond to the first four proto- 
vertebrae and one for each following protovertebra. He “ascertained in an absolute 
manner that during the metamorphosis of the Muraenoids the number neither of the 
myomeres, nor of the vertebral arches, nor of the spinal ganglia, is subjected to any 
change.” He referred the following Leptocephali to their respective species: 
Leptocephalus brevirostris Anguilla vulgaris. 
Leptocephalus stenops (in part), morrisii, punctatus Conger vulgaris. 
Leptocephalus haeckeli, yarreli, bibroni, gegenbauri, koilikeri, stenops (in pariJ.Congromurtena mystax. 
Leptocephalus ttenia, inomatus, diaphanus Congromuraena balearica. 
Leptocephalus kefersteini Numerous species of Ophichthys. 
Leptocephalus longirostris and Hyoprorus messanensi.s Nettastoma melanuruni. 
Leptocephalus oxyrhynchus Saurenchelys cancrivora. 
The eggs described by Raffaele have all the characteristics of pelagic eggs, and the 
one to be described here, which is very closely related to No. 6 of Raffaele, is 
certainly a typical pelagic egg. Grassi also secured the eggs of eels on the surface at 
Naples. Why, under the circumstances, he concludes that “they remain at great 
depths in the sea, and only exceptionally, for unknown reasons, some of them mount 
to the surface ” is not apparent. Being lighter than sea water, having oil-spheres, and 
being in all respects typical pelagic eggs found on the surface, we must conclude 
that “if fertilization takes place at great depths” it must be “only exceptionally, 
for unknown reasons,” that they remain at the great depths. The fact that Raffaele 
never secured eggs younger than when the gastrula was well formed would favor the 
supposition that they were fertilized at a great depth and rose slowly in the water. 
Cunningham’s interesting observations on the conger eel, if they are generally 
true for eels, would account for the fact that ripe females are rarely taken, and those 
of Schmidtlein and Hermes point against the supposition of Grassi that the females of 
eels in general ripen only at depths of at least 500 meters. 
Schmidtlein 1 2 and Hermes 8 both noted that female conger eels sometimes died in 
confinement, the result of excessive development of ovaries which were not emptied. 
In 1888 Cunningham 3 wrote: 
No one has yet, I believe, seen the fertilized egg of either the eel or the conger, although the 
ovaries and testes have been recognized and described. 
He had not at that time found a male conger. In a later paper 4 he gives a 
general resume of the work done on the conger. He himself found a perfectly ripe 
male 45 cm. long on December 13. Its eyes were strikingly prominent and its mouth 
short and broad. On December lb, among 9 congers caught, one 48 cm. and one 
1 Schmidtlein, R. 
Beobachtungen fiber Trachtigkeits- und Eiablage-Perioden verschiedner Seethiere. Mitth. aus der zool. Station su 
Neapel. I, p. 135, 1879. (Young conger eels scarcely 3 cm. long are captured in the middle of April.) 
Beobachtungen fiber die Lebensweise einiger Seethiere innerhalb der Aquarien der zoologischen Station. Mitth. aus 
der zool. Station zu Neapel. I, p. 492. (Ripe female conger eels sometimes come to the surface and die from the 
presence of excessive numbers of ripe eggs, which for unknown reasons are not expelled.) 
2 Hermes, Otto. 
Zoologischer Anzeiger, vol. iv, 1881. 
The Propagation of the Eel. Rept. United States Fish Commission, 1879, pp. 457-463, 1882. Translated from circula- 
No. 6, November 25, 1880, of the Deutscher Fischerei-Verein. 
The Migration of Eels. Rept. United States Fish Commission, 1884, p. 1123, 1888. 
3 The Breeding of the Conger. Journ. M. B. A., old series, No. 2, p. 245, 1888. 
,On the Reproduction and Development of the Conger. Journ. M. B. A., new series, n, p. 16, 1891. 
