of the Fishery Board for Scotland. 



20S 



(1) That the present view, that the mont^e (or eels coming up into the 

 fresh waters) includes only females, cannot be upheld : both males and 

 females are included. 



(2) The male at its full growth, like the female, is not only in the lower 

 reaches of the rivers and in the fjords and coast waters, but likewise in 

 inland seas and other waters. 



As to the numerical proportion of males to females, different results 

 have been found in different localities. Of 258 eels from Chroggia and 

 Comacchio, examined by Syrski in 1874, the males and females were in 

 about equal proportions ; the greatest length of the former was about 

 430 mm., while the latter were of all sizes up to 1050 mm. Jacoby found 

 in 1887 that among 1200 eels from the brackish waters of the lagoons of 

 Comacchio, 5 per cent, were males, while among those less than 15 inches 

 (375 mm.) 20 per cent, were males. In 1880 Dr Hermes discovered 8 

 males in a lot of 36 eels from Wismar, Denmark. At Rugers on the 

 Baltic, in the same year, Dr Hermes found that in one lot of 137 eels, 

 44J percent, were males. Among 250 eels, from 11-15 inches in length, 

 procured by Hermes at Cumlosen on the Elbe, 5 per cent, were males. 

 Brunn* was able to ascertain that about 80 per cent, of the small eels that 

 are caught in the lower Elbe belong to the male sex. In a collection of 

 60 eels, varying in size from llf-21f inches, procured from the estuary 

 of the Eden in October 1894, there were 23 males and 38 females. The 

 males measured from 12-16 inches, and the females llf-21f inches in 

 length. 



External Differences between Male and Female Eels. 



Much attention has been given to the attempts to find external sexual 

 differences in eels. Difference of colour, when taken together with certain 

 anatomical differences, was considered to be of value in the separation of 

 the sexes. The male was very often, invariably by Jacoby, found to 

 have a metallic sheen on the sides of the body. The females were as a 

 rule of lighter coloration on the back than the males. A very great 

 difference in the maximum size of the eels of different sexes has been 

 noticed. No male eel has been found whose length exceeded 20 inches 

 (500 mm.) ; females are commonly got over 3 feet (900 mm). Jacoby f 

 summarises the external sexual differences as follows : — The most important 

 differences between live eels having an ovarium and those having a lobe- 

 organ are : — 



(1) That of the length and size. Syrski says that the largest eels 

 with lobe-organs discovered by him measured 430 mm. (17^ in.). 1 

 have however, both at Trieste and Comacchio, found eels with this organ 

 measuring 450, 460, 470, 480 mm. (18-19J inches). All eels larger than 

 this have, so far at least, been invariably found to be females. The out- 

 ward differences are — 



(2) The broader snout of the female, in contradistinction to the narrotv 

 extended or short pointed snout of the eel with the lobe-organ. 



(3) The lighter colour of the female, green on the back, and yellow or 

 yellowish on the lower side, the back of the male being generally a dark 

 green, often almost black, with its sides having invariably a metallic 

 glitter. I have found eels having a bronze colour, which were always eels 

 with a Syrski organ, and their lower side white. 



(4) A very striking difference is the height of the dorsal fin. All 



* From ' De strijd over de mannetjes-alen,' Medcdeelingen over Visscherij, Dr P. 

 P. C. Hoek, Helder, 1894, p. 132. 

 t Jacoby,' The Eel Question,' Report U.S. Fish. Comm., 1879. Washington, 1882. 



