92 



BULLETIN OF THE UNITED STATES FISH COMMISSION. 



have a more delicate tissue, and an almost mucous appearance, and con- 

 tain the eggs with the germinative vesicles. 



The deferent canals and the genital orifice are closed in young eels of 

 the male sex, and open simultaneously with the development of the lobes. 



In the male eels examined by me from March to October, I have found 

 individuals of 400 millimeters and more in length, whose genital orifice 

 and deterent canals were invariably open, while in some of the smaller 

 ones they were closed and in others open. 



^'■■■A^.^L v^r- >'^^' ■^''^■'  .^ "■■'■/.,>;>; 



.U^v..." 



f a h 



Pig. 7. Piece of the testicle (one hundred and 

 sixty times enlarged), showing the 

 vascular tissue and the bmall granules. 



Fig. 8. Anal jjart of the male eel, enlarged twice, 

 a. Straight intestine. 

 6. Fissura recto-vesicalis, covered by the outside 



wall of the seminal pouch. 

 cc. Outlet of the anterior and posterior part of 



the deferent canal in the pouch. 

 d. Urinary bladder. 



Of the 258 eels examined by me, the males and females were in about 

 even proportion; the greatest length of the former was about 430 milli- 

 meters, while the latter were of all sizes up to 1,050 millimeters, which 

 shows that the males are smaller than the females. 



b. EXTERNAL CHARACTERISTICS. — JACOBY. 



The external differences presented by living eels (remarks Jacoby), 

 corresponding to the presence of an ovary and the supposed male organ, 

 are very interesting. 



The most important, writes Jacoby, is (1) the difference in the size and 

 length of the animal. Syrski states that the largest eels found by him 

 with the supi)osed male organ measured about 17 inches, 430'""\ I have, 

 however, found specimens with this organ at Trieste and in Comacchio 

 which measured 17 to 19 inches, 450 to 480^°™. All the eels which ex- 

 ceeded this size, for instance those which were over 3 feet in length, 

 1™, many of them growing to the thickness of the arm of a strong man, 

 have been hitherto found to be females. The other recognizable ex- 

 ternal character in the female are (2) a much broader tip of the snout 

 in comparison with the small, either attenuated or short and sharply 

 pointed, snout of the eel with the supposed male organ; also (3) a clearer 

 coloration in the female, usually of a greenish hue on the back, and 

 yellowish or yellow upon the belly, while the others have a deep darkish 



