HETEROMP, 227 



Characodon from Central Amer. Haphlochilus M'Cl., E. Ind. trop. 

 Afr., temp, and tropical Amer. Fundulus C. at V., killifish, abundant 

 in New World, one in Spain and one in E. Afr. ; allied are the Soutli 

 American Limnurgus, Lucania, Rivulus and Cynolehias ; Orestias 

 C. et v.. East Peru and Bolivia, at an elevation of 13,000 to 14,000 

 ft. ; Jenynsia Gthr., Madonado ; Gambusia Poey, W. Indies, and 

 S. Amer. ; allied are Pseudoxiphophorus and Belonesox of Cent. 

 Amer. ; Anahleps Art., four-eyed fishes, iris with two pupils, swims 

 with part of head out of water, trop. Amer. 



II. Limnophagae. Mandibular bones but loosely joined, intestine 

 convoluted, sexes differentiated, mud-eating, trop. Amer. Poecilia, 

 Mollienesia, Plaiypoecilus, Girardinus. 

 Fam. 33. Amblyopsidae (Heteropygii), Head naked, body with very 

 small scales, barbels absent. Villiforin teeth in jaws and on palate. 

 Adipose fin absent. Pelvic fins small or absent. Vent in front of pectorals. 

 Stomach caecal ; pyloric caeca present. Pseudobranch absent (con- 

 cealed). Fishes of small size living in the swamps and subterranean streams 

 of the United States. Amhlyopsis De Kay, the blind fish of the Mammoth 

 Cave of Kentucky, colourless, 5 inches, eyes and optic nerve very 

 imperfect * ; viviparous ; allied species without pelvic fins are known as 

 Typhlichthys Gerard. Chologaster Ag., with normal eyes and coloured ; 

 swamps and entering caves. 



Fam. 34. Stephanoberycidae, deep sea. 



Fam. 35. Percopsidae. F. w. of N. Amer. ; adipose fin present ; dorsal 

 and anal with a few spines, pelvics abdominal with more than five soft 

 rays, with a trace of pnemnatic duct and with pseudo-branch ; body 

 covered with ctenoid scales. Percopsis Ag., Columbia Eigenm. 



Sub-order 6. HETEROMI (DERCETIFORMES). 



Air-bladder without open duct ; parietals separating the 

 frontals from the supraoccipital ; no mesocoracoid. Pelvics 

 abdominal if present. 



Fam. 36. Dercetidae. Eel-shaped fishes without ordinary scales. 

 Body generally with four series of subtriangular scutes and intermediate 

 scale-like smaller scutes. Head long and jaws produced. Extinct, Cre- 

 taceous. Dercetis Ag., Pelargorhynchus v. d. Marck. 



Fam. 37. Halosauridae, deep-sea forms. Halosaurus, Aldrovandia. 



Fam. 38. Notacanthidae, deep-sea, pelvics abdominal, air-bladder 

 with duct. Notacanthus, Macdonaldia. 



Fam. 39. Lipogenyidae. Deep-sea. 



Fam. 40. Fierasferidae.f Without pelvic fins, vent at the throat ; 

 eel-like, small, shore-fishes of tropical seas, often living as lodgers 

 in cavities of other animals, e.g. Holothurians, starfishes and bivalve 

 molluscs ; often commensal with the pearl oyster ; are harmless to their 

 hosts. Fierasfer Cuv., Encheliophis. Lycodapus Gilbert may be placed 

 near here. 



* Eigenmann, Arch. f. Entwick. Mech., 8, 1899, p. 545. 

 t Emery, Fauna und Flora d. Golf. v. Neapel, 1880. 



