ELOPS. — THE SUB-GENERA. 281 



herring, joined to the prolongation of the last ray of the 

 dorsal into a filament j yet in Megalops the mouth is 

 strongly armed with teeth, and the belly is neither com- 

 pressed nor carinated ; while in Clupea the jaws are all 

 but toothless, and the ridge of the belly is sharp and 

 serrated. Clupea, in its most typical examples, repre- 

 sents, of course, the whole group ; so that, whatever 

 minor divisions may, and possibly do, enter into this 

 circle, the prominent variations intimately correspond 

 (so far as the nature of the group will admit) with all 

 that has been said of the primary types of ichthyology, 

 or, rather, when these views are extended, of those of 

 the whole vertebrated circle. 



(242.) Leaving the toothless herrings, we come now 

 to those which have well-defined and often numerous 

 teeth ; the majority of which, also, are without the 

 sharp serrated belly which pervades the whole of the 

 last division. We look upon the Linnaean genus Elops 

 as exhibiting the most typical structure of this group, 

 associating with it Butirinus, as a subordinate form : fol- 

 lowing these we place Megalops, JVotopterus, Trichosoma, 

 and Engraulis, all of which are at once known by possess- 

 ing determinate or well-defined teeth.* There is not 

 sufficient information on these fishes to allow of our 

 tracing the series so effectually as in the last ; but M. 

 Cuvier places them close together t, and we shall now 

 proceed to show how intimately they are all allied. The 

 reader will remember that the genus Thryssa was the 

 only one of the last group which had a wide mouth and 

 distinct teeth ; and that it consequently opened a pas- 

 sage from Chatoessus to the true anchovies. Engraulis, 

 therefore, will be the first type of our present division 

 after leaving Clupea : we restrict this sub-genus to those 

 anchovies of which the common Mediterranean species 



* This must remain questionable in regard to our new genus Trichosoma, 

 the Engraulis Hamiltonii of Gray, Ind. Zool., because, as no description of 

 this fish has been published, we can judge only from the figure ; but as 

 Mr. Gray associates it with the anchovies, we may presume that its teeth 

 are the same. 



f Cuvier's series is as follows : — Notopterus, Engraulis, Thryssa, Mega- 

 lops, Elops, and Butirinus. 



