368 contributions to noeth american ichthyology — ^^iv. 



Order P.-OPISTHOMI. 



{The Spiny Eels.) 



Scapular arch suspended to the anterior vertebrre. Superior pharyn- 

 geals and branchihyals ossified, the third pharyngeal a little larger, 

 the fourth small. Three basal branchihyals ; inferior pharyngeals 

 distinct ; maxillary bone distinct ; supraoccipital separating parietals ; 

 no interclavicles ; symplectic present; prtecoracoid wanting; parietals 

 separated by the supraoccipital; air-bladder, if present, without pneu- 

 matic duct ; dorsal with spines ; ventrals, if present, abdominaL The 

 fishes of this order differ from other PhysocUsti and agree with the 

 Eels in having the scapular arch free from the cranium and attached 

 to the anterior vertebrse. Two families are known. (orrjV(?>5, backward; 

 fc>,ao<r, shoulder.) 



ANALYSIS OF FAMILIES OF OPISTHOMI. 



a. Ventral fius wanting; dorsal fin with the soft portion well developwl. 



Mastacembelid^, 56 (b). 

 aa. Ventral fins abdominal, of nnmerous spines and soft rays; soft portion of the dor- 

 sal fin obsolete NoTACANTiiiDiE, 56 (c). 



Family LVI (Z>).— MASTACEMBELID^. 



{The Spiny Eels.) 



Body elongate, eel-like, naked or covered with very small scales. 

 Mouth oblique, of moderate size, either the snout or the chin being 

 produced in a fleshy appendage ; lower jaw little movable; upper jaw 

 not protractile. Teeth small. Gill-openings restricted to the region 

 below the convexity of the operculum, the upper part of the oper- 

 culum being covered by the skin of the scapular region ; gill-mem- 

 branes free from the isthmus ; gills 4, a slit behind the fourth. Pseu- 

 dobranchioe small or obsolete. Tail isocercal. Dorsal fin very long, 

 the anterior part composed of low, free spines, the posterior of soft 

 rays; anal fin with or without spines; caudal fin separate or not. 

 Ventral fins wanting; pectorals small. Air-bladder present. Bran- 

 chiostegals 6; pyloric coeca 2 {in Mastacemhelus). Fishes of the fresh 

 waters of the East Indies. Genera 2; species about 14. We follow 

 Dr. Bean in attaching provisionally to this family a singular fish from 



