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 (^4. vulgaris), while Pack- 



Fig. 401. A Siluroid Fish, Arius. 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. e. , 

 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 

 Xorth American waters by the catfish and horned pout. 

 The name of the order (from vrfpa, vffjAaros, thread, and 



