346 Bulletin 47, United States National Museum, 



k. Pectoral fins well developed ; skin thick ; skeleton 



firm ; snout moderate ; tail not ending in a 



filiform tip. MUR;ENESOCID;E, XLVIII. 



kk. Pectoral fins wholly wanting ; snout and jaws 



much produced, the upper longer ; jaws 



straight ; skin thin, the skeleton weak ; tail 



ending in a filiform tip ; gill openings small, 



subinferior; teeth sharp, subequal, recurved; 



a long series on the vomer ; deep-sea eels, 



soft in body, black in color. 



NETTASTOMIDJE, XLIX. 



jj. Jaws long and slender, tapering to a point, recurved 

 at tip ; nostrils large, both pairs close in front of 

 eye ; gill openings convergent forward, separate 

 or confluent ; pectorals and vertical fins well 

 developed ; membranes of fins thin, not envelop- 



ing the rays ; skeleton well developed ; deep-sea 



eels. NEMICHTHYID^E, L. 



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



or less fully adnate to the floor of the mouth ; teeth subequal. 



MYRIDjE, LT. 



ff. Tip of tail without rays, projecting beyond the dorsal and anal fins (not 

 filiform) ; posterior nostril on the edge of the upper lip ; anterior 

 nostril near tip of snout, usually in a small tube ; tongue usually 

 adnate to the floor of the mouth. Coloration frequently varie- 

 gated. OPHICHTHYID5!, HI. 

 COLOCEPHALI : 



aa. Gill openings small, roundish, leading to restricted interbranchial slits ; tongue wanting; 

 pectoral fins (typically) wanting ; opercles feebly developed ; fourth gill arch modi- 

 fied, strengthened, and supporting pharyngeal jaws. 



1. Scapular arch obsolete or represented by cartilage ; heart not far back ; pectot als want- 

 ing ; skin thick ; coloration often variegated. MURJSNID^E, tin. 



Suborder ENCHELYCEPALI. 

 (THE EELS.) 



The characters of this group are given above. (gygeAvc, eel; KegxiMj, 

 head.) 



Family XLIII. ANGUILLID.E. 

 (THE TKUE EELS.) 



The true eels or Anguillidce are characterized by their scaly skin in 

 association with a conical head and a general resemblance to the Congers. 

 The group is thus diagnosed by Dr. Gill : 



Enchelycephalous Apodals with conical head, well-developed opercular 

 apparatus, lateral maxillines, cardiform teeth, distinct tongue, vertical 

 lateral branchial apertures, continuous vertical fins, with the dorsal far 

 from the head, pectorals well developed, scaly skin, and nearly perfect 

 branchial skeleton. 



The Anguillidce approach more nearly than most of the other eels to the 

 type of the true fishes. In one respect, that of the minute ova and con- 

 cealed generation, however, they differ widely from these. The single 

 genus of living Anguillida is widely diffused in temperate and tropical 

 waters. Unlike the other eels the Anguillidcv freely ascend the rivers, 

 descending to the sea for purposes of reproduction. One genus, with 5 or 

 more valid species. (Murccnidce, genus Anguilla, GUNTHER, Cat., vm,23 

 to 37, 1870.) 



a Dorsal fin inserted well behind base of pectorals, shoulder girdle well developed ; lower 

 jaw projecting. ANGUILLA, 150. 



