LIFE HISTORIES 355 



Sea, but in the day time they are only to be caught at or near 

 the bottom. Between February and May these young eels, 

 which are about two inches in length, reach the coast and begin 

 to ascend the rivers. It has been proved that the ascent com- 

 mences earlier at places nearer to the Atlantic, later at places 

 more remote ; thus in the Severn the ascent commences in 

 February and takes place chiefly in March and April, in Den- 

 mark it does not begin till May. It will be seen therefore that 

 the young fully developed eels which ascend rivers are already 

 nearly a year old ; the Leptocephali were taken in the Atlantic 

 in June and must have been hatched before that, while the 

 earliest ascent is in February following. These young eels 

 therefore are the progeny, not of the adults which went down to 

 the sea in the preceding autumn, but of those which descended 

 the year before that. 



The principal changes of the metamorphosis, stages of which 

 are represented in Plate XXIX., are as follows. In the early 

 Leptocephalus stage the body is very deep from the dorsal edge 

 to the ventral and narrow from side to side, the anus is about 

 one quarter of the total length from the end of the tail, and the 

 dorsal and ventral fins begin at the level of the anus. The 

 mouth is furnished with long larval teeth projecting forwards. 

 These teeth soon disappear. The average length of this first 

 stage is 7'5 centimetres or 3 in. ; the average length of the 

 fully developed and pigmented young eels is 6' 5 centimetres 

 or 2§ in., while some of them are only 2\ in. long. During the 

 metamorphosis the anus and the commencements of the dorsal 

 and ventral fins move gradually forwards, the dorsal fin more 

 than the ventral ; the head does not grow but the body is re- 

 duced to the thickness of the head. During the whole trans- 

 formation the larvae seem to take no food, a fact which accounts 

 for the reduction of size. With regard to the abundance of 

 young elvers ascending rivers the following figures are given in 

 an official report by Buckland and Walpole published in 1876: 

 1400 to 1500 elvers make I lb. ; as I cwt. of elvers are fre- 

 quently taken by one man in one night in the river Severn and 

 hundreds of men are taking them at the same time, some idea 

 may be obtained of the prodigious number that annually enter 

 that river. 



Our knowledge of the eggs of the eel and conger is much 



