220 FISHES. 



The fourth Order of Fishes is that of 



ORDER IV, 



APODAL MALACOPTERYGIANS. 



This order may be considered as forming but a single natural family, 

 that of the 



ANGUILLIFORMES. 



Fishes with an elongated form, a thick and soft skin, which almost 

 renders its scales invisible, and but few bones. They have no caeca, but 

 nearly all of them possess natatory bladders which frequently assume the 

 most singular shapes. The great genus 



MurjEna, Lin. 



The Eels are recognized by the little opercula concentrically surrounded 

 by the rays, all of which are enveloped in the skin, which only opens at a 

 considerable distance back by a hole or species of tube, an arrangement 

 which, by more completely protecting the branchiae, allows these fishes to 

 remain some time out of water without perishing. Their body is long 

 and slender; their scales, as if encrusted in a fat and thick skin, are only 

 distinctly visible after desiccation ; they have neither ventrals nor caeca, 

 and their anus is placed far back. This genus has been successively 

 separated into five or six genera, which we are compelled to subdivide 

 still more*. 



Anguilla, Thunb. and Shaw. — Mur^na, Bl. 



Eels are distinguished by the two-fold character of pectoral fins and of 

 branchiae opening under them on each side. Their stomach is a long 

 cul-de-sac; their intestine is nearly straight, and their elongated natatory 

 bladder is furnished near the middle with a peculiar gland. 



Anguilla, Cuv. — Mur^ena, Lacep. 



The Eels, properly so called, have the dorsal and caudal evidently con- 

 tinued round the end of the tail, forming by their union a pointed caudal. 



* In none of these fishes, to our knowledge, are the opercula or rays wanting, 

 as some authors have thought. The common Murana has seven rays on each side? 

 the Mnr. colubrina has twenty-five. These rays are even very strong in Synbranchus, 

 where the operculum is also complete, and formed of all its usual portions. 



N. B. The Echelos, Rafin., Nov. Gen., p. 63, pi. xv, 1, 3, pi. xvi, f. 2 and 3, must 

 be of two kinds, the first Eels, and the other Congers, without branchial opercula — 

 but we doubt the truth of this character. 



