294 FISHES CHAP. 
Another example of these interesting structures occurs in 
Chanos salmoneus and a few other Clupeidae? in the shape of a 
coiled gill-like organ (“ gill-heix”), which is supported by the 
dorsal segment of the fourth branchial arch, and enclosed in a 
similarly curved caecal extension of the branchial cavity. Each 
gill derives its blood from the fourth afferent branchial artery, 
the corresponding efferent vessel joining the fourth efferent 
branchial artery. A similar spirally-coiled “ gill-helix ” is found 
Iu. 171.—Accessory respiratory organ of Clarias, as seen after the removal of the left 
operculum. a, Anterior arborescent organ ; }.a'~+, the first four branchial arches 
and their holobranchs ; d.6.c, dorsal extension of the left branchial cavity ; /, 
modified gill- filaments ; op, base of the operculum ; p, posterior arborescent 
organ. 
also in Heterotis ehrenbergii,, amongst the Osteoglossidae, and in 
several species of Characinidae.* 
In other Teleosts the accessory breathing organ assumes the 
condition of paired lung-like outgrowths of the branchial cavity. 
Thus, in one of the Symbranchidae, the Indian “Cuchia Eel ” 
(Amphipnous cuchia)# there is a pair of small bladder-like sacs, 
with membranous and vascular walls, each of which opens into 
the branchial cavity above the first gill-cleft, and is supplied 
with blood by the afferent branchial artery of the gill-less first 
branchial arch. An extreme modification in the same direction 
1 Hyrtl, Denksch. k. Akad. Wiss. Wien. xxiii. 1868, p. i.; ibid. x. 1855, p. 48. 
2 Hyrtl, ibid. viii. 1854, p. 185. 
* Hyrtl, ibid. xxi. 1863, p. 7; Sagemchl, Morph. Jahrb. xii. 1887, p. 307. 
4 Taylor, Edin. Journ, Sci. v. 1831, p. 33; Hyrtl, Denksch. k. Akad. Wiss. 
Wien. xiv. 1858, p. 39. 
