FAMILT, IX— STMBBANCHID^. 655 



Family, IX— SYMBKANCHID^. 



Gill-openingg confluent into a single slit, which is situated on the abdominal surface. Gills well 

 developed or rudimentary. Body elongated. The humeral arch may or may not be attached to the skull. 

 Margin of the upper jaw formed by the premazillaries, the mazillaries being internal and parallel to them. 

 Barbels absent. Palatine teeth, when present, in a single row or a narrow band. Vertical fins rudi- 

 mentary, in the form of mere folds of skin, and no paired ones. Scales, if present, minute. Vent far 

 behind the head. An accessory breathing sac present or* absent. Air-vessel absent. Bibs present. Stomach 

 destitute of a blind sac. No pyloric appendages. Ovaries with oviducts. 



The Families Symbrcmehidce and Mu/rcBnidce belong to the Physostomi apodes of some authors, and the 

 former tropical family is fairly represented in the continent of India, whereas the latter is more numerous in 

 the seas than in the fresh waters. 



Geogrwphieal distribution. — Fresh and brackish waters of tropical Asia and America ; also Western 

 Australia and Van Diemen's land. 



SYNOPSIS OP GENERA. 



First group — Amphipnina. 



Humeral arch not attached to the skull : an accessory breathing apparatus. Scales present. 



1. AmpJwpnous. Palatine teeth in a single row, p. 655. 



Second group— Symbeanchina. 

 Humeral arch attached to the skull. No accessory breathing apparatus. Scales absent. 



2. Monopterus. Grills rudimentary, p. 656. 



3. Symbranchus. GUIs well-developed, p. 657. 



First g^oup — ^Amphipnina. 

 Humeral arch not attached to the skull. An accessory breathing apparatus. Scales present. 



Genus, I — Amphipnous. Muller. 



Fnev/mahroMchus, McClelland. 7 , . .7 



Brcmehdostegals six. Gill membranes almost entirely grown to the isthmus, and hamng a single transverse 

 opening. Three branchial arches with the lamince rudimentary, dimded by narrow slits. A respiratory air sac exists 

 on the neck behind the head communicating with the gill camty. Palatine teeth in a single, well-developed row. 

 Scales present and arranged in longitudinal rows. 



This amphibious fish, when kept in an aquarium, may be observed to constantly rise to the surface for 

 the purpose of respiring atmospheric air direct. It usually remains with its snout close to the surface and in 

 like manner lies in the grassy sides of ponds and stagnant pieces of water, so that without trouble it may 

 obtain its modicum of air. McClelland observed (Cal. Joum. Nat. Hist, v, p. 195). "I have had two live 

 GucUas by me now for a period of twelve months ; they are still as well as when I first obtamed them, though 

 from an ignorance of their proper food, as well as a desire to know how long they are capable ot existing 

 without any, they had nothing to eat during that period to within the last few months, when some smaU fish 

 and shrimps were put alive into the vessel." 



In Amphipnous euohia, we find " that of all the arches the second alone possesses laminae for the purposes 

 of breathing : and those consist merely of a few long fibrils attached to the middle of the arch and occupying 

 but a very small extent of its surface : the third supports in the place of laminae, a thick and semi-transparent 

 tissue, which in large individuals of the species possesses a fringed or denticulated appearance on its edge ; 

 whilst the third and fourth are bare, having only the membrane that fills up the space between the arches 

 reflected over them. The principal organs of respiration are two. small bladders, which the animal has the 

 power of filling with air, immediately derived from the atmosphere. They are placed behind the head, one on 

 ^ch side of the neck, above the superior or vertebral extremities of the branchial arches, and are covered over 

 by the common integument, presenting externally when distended with air, two protuberances of a round 



shape They present, when separated from their surrounding attachments and inflated with air, 



thin, transparent, membranous parieties, resembling the posterior portions of the lungs ot a serpent. . . . 



