THE EEL FAMILY. 



449 



They claim to have actually followed the transformation into 

 the ■ elver,' but they unfortunately did not preserve any at their 

 first stage. 



In the accompanying diagrams are shown the transition- 

 stages already obtained. The first two give the appearance 

 presented by Leptocephalus brevirostris at two different stages. 

 Fig. 44 gives the transition form which may be caught during 



Fig. 42. Leptocephalus brevirostris. Nat. size. After Grassi. 



Fio. 43. The same Leptocephalus at a later stage. Nat. size. Grassi. 



Fig. 44. Transition-stage or hemi-larva of the eel. Nat. size. Grassi. 



Fig. 45. Young eel (elver) after the transformation. Nat. size. Grassi. 



winter in the sea, and it presents intermediate characters 

 between Leptocephalus and the ' elver ' which is figured below 

 it, and which can be caught in the course of migration 

 from the sea into fresh water. There is no pigment, and the 

 transformation to the normal elver of our rivers is effected by 

 the development of definite black pigment and by a reduction 

 in size. No young eel has been found, as already remarked, less 

 than 5 cm. in length, but the colourless elver has an average 

 length of 6'7 cms. Grassi sums up his observations as 

 follows: 'Anguilla vulgaris, the common eel, matures in the 

 depth of the sea, where it acquires larger eyes than are ever 

 M. P. 29 



