2886 Bulletin 47, United States National Museum. 



D. Skin covered with rudimentary embedded scales, usually linear 



in form, arranged in small groups, and placed obliquely 

 at right angles to those of the neighboring groups ; pec- 

 torals and vertical fins well developed, the latter confluent 

 about the tail; lateral line present; posterior nostril in 

 front of eyes ; tongue with its margins free. 



E. Gill openings well separated; branchiostegals long, bent up- 



ward behind. 



F. Gill openings lateral and vertical; snout conic, the jaws not 



very heavy; gape longitudinal; lips thick; lower jaw pro- 

 jecting; teeth in cardiform bands on jaws and vomer; 



eggs minute XLIII, ANGUILLID.E, 346. 



FF. Gill openings horizontal, inferior. 



G. Snout very blunt, with very strong jaws; gape transverse; lips 



obsolete; teeth blunt, in 1 series, on jaws only. 



XLIV, SlMENCHELYIDyE, 348. 



GG. Snout conical and slender, the jaws of moderate strength; gape 

 lateral; lips obsolete; tongue but little developed; teeth 

 acute, in bands on jaws and vomer. 



XLV, ILYOPHIDID.E, 349. 



EE. Gill openings inferior, very close together, apparently confluent ; 

 branchiostegal rays abbreviated behind; head conical; 

 tongue small ; posterior nostrils in front of eye. 



XLVI, SYNAPHOBRANCHID^E, 350. 

 DD. Scales wholly wanting; eggs (so far as known) of moderate 



size, much as in ordinary fishes. 



H. Tip of tail with a more or less distinct fin, the dorsal and anal 

 fins confluent around it; the tail sometimes ending in a 

 long filament. Coloration almost always plain, brown- 

 ish, blackish, or silvery, the fins often black-margined. 

 I. Posterior nostril without tube, situated entirely above the upper 



lip. 

 J. Tongue broad, largely free anteriorly and on sides; vomerino 



teeth moderate. 



K. Pectoral fins well developed; body not excessively elongate; 

 lower jaw not projecting; anterior nostril remote from 



eye XLVII, LEPTOCEPHALID.K, 352. 



JJ. Tongue narrow, adnate to the floor of the mouth or only the tip 

 slightly free; vomerine teeth well developed, sometimes 

 enlarged. 

 L. Jaws not attenuate and recurved at tip; gill openings well 



separated; anterior nostril remote from eye. 



M. Pectoral fins well developed ; skin thick; skeleton firm; snout 

 moderate; tail not ending in a filiform tip. 



XL VIII, MUR.ENESOCID.E, 358. 



MM. Pectoral fins wholly wanting; snout and jaws much produced, 

 the upper longer; jaws straight; skin thin and skeleton 

 weak ; tail ending in a filiform tip ; gill openings small, 

 subinferior; teeth sharp, subequal, recurved, a long 

 series on the A r omer. Deep-sea eels, soft in body, black 



in color XLIX, NETTASTOM ATID.E, 364. 



LL. Jaws long and slender, tapering to a point, recurved at tip; 

 nostrils large, both pairs close in front of eye ; gill open 

 ings convergent forward, separate or confluent; pectorals 

 and vertical fins well developed; membranes of fins thin, 

 not enveloping the rays ; skeleton well developed. Deep- 

 sea eels L, NEMICHTHYID^E, 366. 



II. Posterior nostril close to the edge of the upper lip ; tongue more 

 or less fully adnate to the floor of the mouth; teeth sub- 

 equal LI, MYRID*:, 370. 



HH. Tip of tail without rays, projecting beyond the dorsal and anal 

 fins (not filiform); posterior nostril on the edge of the 



