BY J. DOUGLAS OGILBY. 765 



AXGUILLA sp. 



The four specimens of fresh-water eels brought back by Mr. 

 Hedley form an excellent working series, as they vary in size 

 from 236 to 647 millimeters. There can be no doubt as to the 

 specific identity of these four, but the series proves to be of more 

 than ordinary interest as a means of demonstrating the insignifi- 

 cance of some of the characters which have been considered of 

 the highest importance in the determination of species among 

 these fishes. Omitting all reference to such characters as are 

 dependent upon the size of the eye, since it is now understood 

 that this is co-ordinate with the degree of development to which 

 the sexual organs ha^■e attained in each individual, I submit the 

 following analysis, showing the principal differences which exist 

 between the larger New Caledonian specimen and the three 

 smaller ones. 



Specimen a, 647 millimeters. 



Head 6§ in the total length, lyo "^ ^^^^ trunk, y^ more than the 

 space between the gill-opening and the origin of the dorsal, 

 and i less than the distance between the latter and the vent; 

 cleft of mouth 3 in the length of the head ; space between 

 origin of dorsal and tip of snout 3| in the total length; 

 pectoral 31 in the head. 



Specimens b-d ; 236-345 millimeters. 



Head 7i to 7| in the total length, 2 to 2^ in the trunk, \ to ^ 

 less than the space between the gill-opening and the origin 

 of the doi'sal, and \ to f mor^e than the distance between the 

 latter and the vent ; cleft of mouth 3| to 34 in the length of 

 the head ; space between origin of dorsal and tip of snout 

 2y-^ to 3i in the total length; pectoral 3^^- to 4i in the head. 



In all the specimens the lateral bands of maxillary and mandi- 

 bular teeth are divided into two sections by a naked longitudinal 

 groove, the outer section consisting of a single series of enlarged, 

 closely set, cutting teeth — similar to those of Leptocephabis — 

 with the occasional addition, in the younger examples, of a limited 



