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morphosis, during which period no food is taken, has thus lasted about one year. As 

 will be remembered, the Stage l, Leptocephalus brevtrosirts, was found already in May 

 in the Atlantic off the coasts of Europe. 



We are now in a position to give the following list showing the order of appearance 

 of the various developmental stages, so far as the investigations extend as yet: 



Development 

 Stage 



Period of occurrence 



May — August, Sept. 

 August — Sept. inclusive 

 August— Sept. inclusive 

 August — Nov. inclusive 

 Sept., Nov. — April, Mayi 

 May, June, July = 



Place of occurrence 



Atlantic Ocean off West Europe in deep water 



; do, or nearer coasts of Europe 



Near coasts of Europe in shallower water 

 Coasts of Europe in fre.sli, brackish or salt water 



Mode of life 



Pelagic 



Partly pelagic 

 On bottom 



We thus see that the various developinental stages of the eel follow after one 

 another in a quite definite chronological order, in such a way that definite 

 pevelopmental stages correspond to definite periods of the years. This 

 gives us reason to believe that the eel like most other species of fish we know about 

 has its main spawning in certain definite months of the year-*, and that the spawning is 

 therefore not spread evenly over the whole year as one might perhaps expect, seeing 

 that we have here a species living in great depths where the changes in the year's 

 seasons are very insignificant. 



After thus giving a general description of the biology of the tiny eel-fry, I may 

 mention the differences in regard to the appearance of the young eels on the different 

 coasts of West and North Europe. 



I may first mention several conditions which make a comparison difficult between 

 the data from the different countries and regions, namely, firstly, that the descriptions of 

 the ascent do not always deal with the youngest elvers. In some reports for example, 

 it is the young eels of 6 to 8 inches long and more which have been seen ascending 

 the rivers, and what are in many cases called the "montée" are thus not the first year's 

 elvers. In short "montée" is not a sufficiently exact biological term. It is therefore very 

 necessary to indicate what I mean by "montée", so as to show that no comparison is 

 made between things with cannot in reality be compared. By "montée" I understand 

 the small elvers of ca.6 — ca.8 centimeters in length which are in Stage 5 

 or 6 and which ascend into the fresh water in the winter or spring and 



1 West of the British Isles the fifth stage has not hitherto been found earlier than in November, whereas 

 in the brackish bays on the north coast of Spain this stage begins to appear in October or September. 



2 It should be remembered that according to V.^ILLANT, the elvers may complete the metamorphosis from 

 the 5th to 6th Stage more quickly, if they enter the fresh water earlier in the year. 



3 Of the first 5 developmental stages the ist and 5th are obviously those of longest duration. On the 

 other hand, the 2nd— 4th, the true transformation-stages during which the reduction in length takes place, seem 

 to pass relatively quickly. 



4 This naturally does not mean that all the North European eels spawn in the same week or month, but 

 only that the majority of them probably spawn at the same period of the year. 



