434 



ANIMAL LIFE-HISTORIES 



the name of Leptocephalus, and supposed to be either a distinct 

 species, or else young fishes which have developed abnormally. 

 The particular sort with which we are here concerned {L. brevi- 

 7'ostris, fig. 959) is distinguished by the shortness of its snout, and 

 the Italian naturalists named above have been able to show that 

 it gradually assumes a cylindrical though still scale- 

 less form, and undoubtedly grows into an eel. 

 From February to May vast multitudes of these 

 young eels, known as "elvers" or "eel-fare", 

 - b. ascend our rivers, those of them which survive 

 reaching the adult state in fresh water, never 

 returning to the sea again, except to spawn. It 

 has also been proved that another kind of Lepto- 

 cephalus (Z. Morrisii) is the larval stage of the 

 marine Conger Eel {Conger vulgaris). It is some- 

 times taken on our own coast, and has received 

 I I the name of Morris. 



t^ 



Fig. 959.— Larval Eel 

 {Leptocephalus brevi- 

 rostris); h., heart; b., 

 body-cavity; i., intes- 

 tine; i-a. , intestinal 

 aperture; ;;;., muscles. 



LIFE-HISTORIES, &c., OF AMPHIBIANS 

 (Amphibia) 



Some few members of this class are viviparous, 

 but the vast majority lay eggs which usually hatch 

 out into aquatic larvse, familiarly known as " tad- 

 poles " or " pollywogs ". The life-history of the 

 common Grass Frog [Rana tevtporaria) has been 

 briefly described in an earlier section (see vol. i, p. 254). Amphibian 

 eggs contain a considerable amount of food-yolk, and there are 

 not infrequently special protective arrangements, in which case 

 comparatively few are produced. We will consider in succession 

 some of the more interesting facts relating to Tailed Amphibians 

 (Urodela), Tailless Amphibians (Anura), and Limbless Am- 

 phibians (Gymnophiona). 



Tailed Amphibians (Urodela). — This group is represented 

 in our country by the familiar Efts or Newts, of which we have 

 three native species (see p. 46). During the spawning season 

 they enter the water for the purpose of laying their eggs, which, 

 as in Amphibians generally, possess gelatinous investments. 

 They are attached to stones or water-plants, and the little tad- 

 poles, which hatch out in a fortnight or so, fix themselves for 



