448 THE EEL FAMILY. 



larva, viz. Leptocephalus hrevirostris (fig. 42), a veritable 

 metamorphosis, with the vent and the urinary opening near 

 the tip of the tail, and with a bod}' so translucent and peculiar 

 that it was considered by Dr Giinther, and others, to be an 

 abnormality. A later stage of this condition is shown in 

 fig. 43. It is remarkable that a large number of the 

 Leptocephali were found in the stomach of the short sun-fish 

 of the straits of Messina. Another change ensues, this larva, 

 according to Grassi, becoming a hemi-larva, the two apertures 

 last named moving forward to the anterior part of the body, 

 which, instead of being deep and flattened like that of a 

 ribbon-fi.sh, becomes thickened and nearly round (fig. 44). By 

 July the hemi-larva assumes the adolescent form. Like the 

 American paradoxical frog, which is less than its tadpole, the 

 larva and hemi-larva have a greater length of body than the 

 young eel or elver into which they are transformed (fig. 4.5). 



The post-larval leptocephaline stage does not occur in the 

 nets in spite of the abundance of parent eels in British rivers, 

 and this also may be accounted for by a burrowing habit, 

 though the perfect transparency suggests a pelagic habit, and 

 as a matter of fact a specimen of L. hrevirostris has been caught 

 in the North Atlantic. 



Grassi and Calandruccio have been enabled to obtain speci- 

 mens of L. hrevirostris in two ways ; firstly, by taking advantage 

 of the remarkable currents at Messina, which at times stir up 

 the sea-bottom and from it a number of deep-sea fishes and 

 Leptocephali, and secondly, by opening the stomach of a 

 certain deep-sea fish named the short sun-fish {Orthagoriscus 

 mola), common in the straits of Messina. Their examination 

 of Leptocephalus hrevirostris, obtained in these ways, brought 

 out a number of anatomical resemblances to the common eel. 

 Of these we may note : 



1. Vertebra not exceeding 117 in the larva, enumerated 



by reference to the myotomes, spinal ganglia, etc. 



2. Rays of pectoral fins the same in number. 



3. No pigmentation in larva nor in ' elver.' 



4. Presence of lateral branch of 5th cranial nerve. 



