Contributions from the Biological Laboratory of the U. S. Fish Commission, 
Woods Hole, Massachusetts. 
THE EGG AND DEVELOPMENT OE THE CONGER EEL. 
By CARL H. EIGENMANN, 
Prof essor of Zoology , University of Indiana. 
On July 31, 1900, at 10 o’clock a. in., the U. S. Fish Commission schooner 
Grampus, while on the tile-fish grounds about 30 miles south of South Shoal, secured 
some pelagic fish eggs. These egg's were collected by Dr. Porter E. Sargent. 
Among them were many which he supposed to be the eggs of the tile-fish, which 
they resembled in many respects. 1 They were brought to the Woods Hole labora- 
tory on August 1. It was soon seen that they were the eggs of some eel, and since 
no eel eggs had been observed in American waters, in fact, none outside a limited 
region in the Mediterranean, it seemed doubly desirable to follow their development. 
When the eggs were secured, the gastrula was said to cover about half of the 
yolk. On August 1 the tail was well developed. During the night between August 
2 and 3 many of them hatched. The last one died in the night between August 13 
and 11. The eggs were divided into two lots on August 1. Some were left in running 
sea water, others placed in a shallow dish of standing water. Since, on August 2, 
many of those in the running water had died while none of those in standing water 
perished, they were all placed in standing water, which was occasionally changed. 
Before describing these eggs more in detail, a brief review of the eel-development 
question may be given. The ancient history is given fully by Jacoby. 2 The modern 
history begins with the discovery of Raffaele, 3 who in 1888 described five species of 
pelagic fish eggs secured during August, September, October, and November, which, 
on account of the character of the larva? they produced, he referred to species of eels. 
This is the first description of the developing eggs of any eel-like fishes. The common 
characters of the eggs described by Raffaele are: (1) Their large size; (2) the large 
peri vitelline space; (3) the delicate membrane lacking pore canals and usually with 
iridescent reflections; (1) the vesicular yolk. They differed from each other in size 
and in the possession or absence of an oil -sphere. 
The eggs and larva? derived from the eggs secured by Raffaele. were characterized 
as follows: No. 6 had a large peri vitelline space, diameter of the eggs 2 to 2.5 mm., 
diameter of thevitellus 1.20 to 1.50 mrn.,1 to 3 oil-spheres of 0.30 to. 0.35 mm. The 
larva developing from this possessed 72 (or 73) abdominal segments. No. 7 had a 
'Ripe eggs taken from a tile-fish and preserved in formalin measure as follows: The yellow oil-sphere 0.2 mm., the 
yolk 1.09 mm., from membrane to membrane 1.25 mm. The eggs are much smaller than those of the eel here described. 
2 Report U. S. Risk Commission, 1879. 
3 Le Uova Galleggianti e le Larve dei Teleostei nel Golfo di Napoli. Mittheilungen aus der Zool. Station zu Neapel, 
8, pp. 1-84, tav. 1-5. 
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