EELS OF THE GENUS CONGER KANAZAWA 221 



overlooked. All of the compressed teeth m the outer row of one half 

 of the upper jaw were counted. The first vertebra that has a com- 

 plete haemal arch was counted as the first caudal vertebra. 



Quantitative characters which are diagnostic on a subspecies level 

 are presented graphically in figure 3, following the methods of Hubbs 

 and Hubbs (1953, p. 51). 



Diagnostic Characters 



Origin of dorsal fin : The congers can roughl}'- be separated into 

 three groups on the basis of the position of the origin of dorsal fin: 

 (1) species with origin of dorsal fin anterior to pectoral fin tip — 

 cinereus, erehennus, and mynaster; (2) species with origin of dorsal 

 fin posterior to tip of pectoral fin — jordani, orbignyanus, vnlsoni, and 

 philippinus ; and (3) species with origin of dorsal fin above posterior 

 tip of pectoral fin — all the remaining species. There is great varia- 

 tion within species and considerable overlap among some species 

 in regard to this character; however, within limits of variation, it is 

 of importance (table 1). Previously the origin of dorsal fin in relation 

 to pectoral fin tip had been the main character for distinguishing 

 species. 



Pectoral fin rays: The range of variation for all species is from 

 14 to 21 rays, but for a single species only 4 to 5 rays (table 2). 



Vertebrae: The range of variation of the number of vertebrae 

 (table 3) is from 127 to 163, with philippinus and esculentus on the 

 lower end of this range and orbignyanus, conger, verreauxi, and tri- 

 poriceps on the upper end. Great care must be taken in order to 

 recognize eels with regenerated tails for they have great powers of 

 forming new ones; however, new vertebrae are not regenerated. 

 The joining of the new caudal fin with the dorsal and anal fins is so 

 well blended at times that it is difficult to distinguish some specimens 

 with regenerated tails. 



Sensory jwres and organs: The sensory pores of the latoi'al line 

 and cephalic pore systems provide characters which differ in several 

 species. The terminology used in the description is shown in figure 

 1a-c and was adapted from Allis (1903). The external pores on the 

 head open directly into a pouchlike tube (y) which connects it with 

 the lateral sensory canal; however, some of these pouches lack this 

 external opening. There are generally six infraorbital pores in the 

 genus; however, two species, cinereus and triporiceps have an ad- 

 ditional one to three more pores in the postorbital series which is the 

 dorsal extension of the infraorbital series (i^, i*, i^). All the species 

 have the sixth infraorbital pore directly behind the rictus of jaw ex- 

 cept cinereus, which has it above and behind the rictus (c). All the 



