DISCUSSION OF SPECIES AND THEIR DISTKIBUTION. 137 



* No scales. Jaws even. Teeth present or absent on vomer Lkptocf.piialid.k 



» Scales present, minute. Lower Jaw projecting. Vonierinc tci-tli [ANi;rii.Lii>.E] 



b. Gill openiufjfs borizontal, inferior. Scales present. Lips i)l)solete, or nearly so. 



* Snout obtuse. .Jaws powerful. Teeth in jaws blunt, iniiserial, with none on vomer. 



SliME.VCIlKI.VID.E 

 ** Snout conical. Jaws uroilerat(^ly stroni;. Teeth sharp, in bands in jaws and on vomer. 



Il.YUl'IlIU.li 



2. Gill openings inferior and <-()ulluent. 

 a. Head conical ; tongue small. 



* Posterior nostrils chise to eye. Branehiostegals siKutcncd SYNAPin)nn.\Ncmi>A; 



B. Pectoral fins absent. 



1. Gill openings distinct, lateral. Scales wanting. Mouth nbliciue, with pnijecling lower jaw 

 and short obtnsi' snout. 



a. Bodyand tail very elongate. Teeth in bands in jaws and on vomer Heteuoco.vgkidje 



II. Tongue narrow, not free. No scales. 

 Gill openings rather wide. 



A. Pectorals strong. 



1. End of tail normally surrounded by vertical fins. *Skelet<ra firm. Skin tliick. 



a. Jaws moderate. Vomer dentigerous MfR/F,NESocrD.E 



* Dorsal and anal well developed MiirtineftociiKe 



** Vertical fins scarcely developed except on tail ISIilbixniKi'. ] 



B. Pectorals moderate, weak, or absent. 



1. End of tail more or less free. 



a. Posterior nostrils in lip or near it; anterior one sometimes tubular OriiiCHTHYlD.f; 



* Fins present, at least on back ilphhhthyinw 



** Fins absent Sphaijebrarichinie 



2. Tip of tail more or less surrounded. 



a. Dorsal well developed ; pectorals sometimes united Myrhne 



Gill openings small, subinferior. 

 A. Pectorals lacking. 



1. End of tail prolonged in a filament. Skin thin. Skeleton weak. 

 a. Jaws str.aight, slender, the upper longest. 



* Teeth sharp, recurved. Vomer with a long series Nettastomid.e 



Gill openings convergent forward, separate or coutluent. 



A. Pectorals present (in American genera). 



1. Jaws very long, recurved at tip Nemichthyid.e 



Family LEPTOCEPHALID^^. 



Co7igeri(l(F, Kaup, Cat. Apodal Fish, in Brit. Mus.,18r)(), 108. 

 Cougridn-, Jokdan & Davis, Rep. U. S. F. C, 1888 (1891), 658. 

 LeptocephaUda; Gir.L, MS. 



Body terete, modeiately elongate, with tlie tij) ol'the tail iiuliuled between the connate 

 vertical tins. Scales absent. Head large, with strong eqnal jaws. Tongue broad, its ante- 

 rior portion comparatively free. Opercular and branchial bones well developed. Vomerine 

 teeth moderate. Anterior nostril remote from eye. Posterior nostril, near the ej-e, tnbe- 

 less, not touching the lip. Pectorals, well developed. 



This family includes those eels which are scakdess tmd have the tongue largely free 

 in front, the liody moderately elongate, the end of the tail surrounded by a flu, the posterior 

 nostril remote from the upper lip and near front of eye, and the pectoral fins well develo]ied. 

 All the species are plainly colored, grayisii or dusky above, silvery below, and have the 

 dorsal edged with black. 



KEY TO THE GENERA OF LEPTOCEPIIALID.E. 



I. Vomerine teeth in bands, uniform in size; lips thick. 



A. Dor.sal origin behind root of pectoral. 



1. Jaws with outer knife-like row of closely s<>t teeth. Head with incimspicuous nnicons 

 cavities, 

 a. Tail considerably longer than body [ l.EPrc .CEriiAi.rs ( 'o.n-geu] 



B. Dorsal origin over the gill opening. 



1. Jaws with bands of small teeth, the outer not forming a cnttingedge. Bonesof front of head 

 with large mueiferous cavitii'S. 

 a. Tail oue-half to two-thirds of total. Mouth rather small Con-(!K1£MCK.ena 



