OPISTHOMI. 



245 



gaseous expansion. Body riband-shaped ; dorsal fin as long as the body ; 

 anal absent ; caudal feeble, or not in the longitudinal axis of the fish. 

 In the young form some of the fin rays are enormously elongated. Tra- 

 chypterus Gouan ; Regalecus glesne, king of the herrings ; Stylophorus. 

 Fam. 121. Lophotidae. 



Sub order 11. OPISTHOMI. 



Air-bladder without open duct. Operculum well developed, 

 hidden under the skin ; supraoccipital in contact with frontals ; 

 pectoral arch suspended from the vertebral column far behind 

 the skull ; no mesocoracoid ; pelvics absent ; median fins with 

 spines. 



Fam. 122. Mastacembelidae. F.w. fishes almost confined to 

 the Indian and Ethiopian regions ; Acanthopterygian eels. They con- 

 stitute part of the fish fauna of Lake Tanganyika. Mastacembelus, 



Fio. 129. — Lophivs piscatoriiis (after Cuvier and Valenciennes, from Glaus). 



Sub-order 12. PEDICULATI (LOPHIIFORMES). Anglers. 



Head and anterior part of body very large and without scales. 

 The spinous dorsal fin is advanced forwards, composed of a few 

 more or less isolated spines, often transformed into tentacles, or 

 entirely absent ; pelvic fins, jugular with 4 or 5 soft rays, 

 sometimes absent. Gill opening a small foramen in or near the 

 axil, posterior to the base of the pectoral ; pseudobranch usually 

 absent ; gills 2|, 3, or 3| ; air-bladder without duct. The som- 

 actids are elongated, forming a kind of arm which supports 

 the broad pectoral fins and by means of which they are able 

 to walk over moist ground, etc., in search of prey or to burrow 

 in the sand or clasp foreign objects. Marine fishes chiefly of 



