130 The Philippine Journal of Science ms 



d\ Anterior nostrils in a short tube at margin of upper lip ; posterior 

 nostrils usually in upper lip in a valve, flap, or slit just for- 

 ward of or below eye and opening downward. 

 g 1 . Caudal present and confluent with dorsal and anal; anus in 



anterior half of length Myridae. 



g\ Caudal absent; tip of tail not threadlike and projecting beyond 

 dorsal and anal when these are present; anus far back, before 



or behind middle of body Opnichthyidse. 



c\ Tail much shorter than rest of body; heart far behind gills; nostrils 

 superior; dorsal and anal confined to tail, confluent with caudal, 



and often reduced to a low fold - Moringuidae. 



a\ Gill openings small, more or less circular or horizontal slits, widely 

 separated; tongue wanting or closely adnate; opercles feebly devel- 

 oped; fourth gill arch modified, strengthened, and supporting pharyn- 

 geal jaws; skull very narrow Suborder Colocephali. 



6*. Pectorals wanting; dorsal and anal more or less developed or vesti- 

 gial, confluent with caudal, covered with thick skin; teoth in two, 

 three, or more rows when dorsal and anal are vestigial or absent; 

 often large and strikingly colored Mursenidse. 



ANGUILLIDiE 



TRUE EELS 



Local names; Bagobo, casili; Bicol, casili, borirauan; Bontoc 

 Igorot, tjalid; Ibanag, quiuo-t, siging; Ilocano, quioet, igat; Iva- 

 tan, tuna, applied to all kinds of eels ; Moro, casili; Pampangan, 

 talunasan, palus; Sambali, talunasan, talunajan; Tagalog, igat, 

 pabucangbinhi; Tirurei, berrirro; Visayan, casili, bais. 



This is the most primitive family of living eels and is composed 

 of a single genus of plain dark-colored elongate fishes, charac- 

 terized especially by having very small, more or less linear- 

 oblong rudimentary scales, occurring in small groups and 

 placed separately at right angles to the adjacent groups. They 

 are found in fresh and brackish waters of the temperate and 

 tropical regions except those of the western coast of North 

 America, the west coast of Africa, and South America. The 

 "electric eels" of the tropical fresh waters of the last-named 

 continent are related to the catfishes. 



Additional characters are as follows: Body elongate, subcy- 

 lindrical, becoming laterally compressed behind; lateral line 

 well developed; head long, conical, more or less pointed, the 

 small eye well forward and over angle of mouth; teeth small, 

 conical, mostly uniform in size, in rather wide bands on each 

 jaw and a long patch on vomer; tongue free at tip, lips thick 

 and full with a free margin behind, attached by a frenum in 

 front, the lower jaw more or less projecting; gill openings rather 

 small, slitlike, vertical, about as wide as base of the well-devel- 



