444 ZOOLOGY. 
as regards the form of the reproductive glands. ‘The 
ovaries form two ribbon-like masses extending from the 
liver to just beyond the vent and attached by one edge 
to the walls of the body, with the free edge hanging 
downwards. When in spawn the ovary is very thick, 
white, and the eggs can be seen with the naked eye, 
being nearly one half millimetre in diameter. When ripe 
they break through the wall of the gland and drop into 
.the body-cavity, there being no oviduct, and pass out of the 
genital opening situated directly behind the vent. The male 
glands occupy the same position as the ovaries of the female, 
but are smaller, narrower, and distinctly lobulated. Out of 
about six hundred specimens of eels, only four males have 
yet been found in this country. These had testes like those 
described by Syrski in the Italian eel (A. vulgaris), while Pack- 
Fig. 401.—A Siluroid Fish, Avius. Young with the yolk not absorbed. 
-ard detected the mother cells, and Mr. Kingsley observed mov- 
ing active spermatozoa. It is probable that the eel descends 
rivers in October and November, spawning in the autumn and 
early winter at the mouth of rivers, and in harbors and es- 
tuaries in shallow water. By the end of the spring the 
young eels are two or three inches long, and then ascend 
rivers and streams. They grow about an inch a month, and 
the females do not spawn at least before the second year, i. ¢., 
when about twenty inches long. Mr. Mather estimates that. 
the ovary of an eel weighing six pounds when in spawn con- 
tains upwards of 9,000,000 eggs. 
Order 3, Nematognathi.—This group is represented in 
North American waters by the catfish and horned pout. 
The name of the order (from v7ua, vyuaros, thread, and 
