COECILIIDAE 



93 



first to disappear is the third gill, of course by being resorbed ; 

 and the clefts are closed before the creature leaves the egg. Hypo- 

 geopliis not leading an aquatic larval life possesses no tail-fin in 

 the embryonic state, the gill-holes are closed, and the epidermal 

 sensory organs disappear long before the time of hatching. 



Vestiges of gills appear also on the hyoid and on the man- 

 dibular arch, but on the latter they are of very short duration. 

 Those of the hyoid gradually fuse with the first of the branchial 

 gills, and these also concentrate with their bases so that they 

 ultimately seem to spring from one common stem. Brauer 

 remarks that the distinction between internal and external gills 

 seems to be one of degree only ; the hyoidean and mandibular 

 gills namely start from the hinder margin of the arches, just 

 like the internal gills of I'orpedo according to Ziegler, while the 

 other gills start from the sides of the branchial arches. He also 

 found a pair of little swellings behind the last gill-cleft, and an 

 unpaired swelling (corresponding with a double one in Ichthyophis) 

 in front of the vent. Not unreasonably he sees in these swellings 

 the last, very transitional vestiges of the paired limbs. 



Typhlonectes compi'essicaicda of Guiana and Venezuela is one 

 of the largest Coecilians, reaching a length of 18 inches, with a 

 body-diameter of ^ inch. The general colour, as in most of these 

 creatures, is olive brown to black. A sort of adhesive disc sur- 

 rounding the vent occurs in this genus. Peters, who described 

 this species, found in one female six embryos of comparatively 

 enormous size, one of them being 157 mm. (more than 6 inches) 

 long, and 12 mm. thick, and devoid of a tail-fin. Instead of 

 lateral gill-openings there is a " bag " on each side 5 5 mm. long, 

 upon which is distributed a blood-vessel. The Sarasins have 

 examined the same specimen : The gills are not a bag, but con- 

 sist of two flat, unbroken membranes which are closely connected 

 with each other. In fact the outer gills of all Amphibia may be 

 said to begin in the shape of small bags, whence sprout 

 secondarily the gill-fringes ; but in Typhlonectes they form these 

 flaps instead of growing into the usual three gills. The embryos 

 have no epidermal sense-organs, but plenty of skin-glands. Prob- 

 ably when born they take at once to terrestrial life, the flaps are 

 possibly shed at birth, and there remains a little cicatrix. 



Dcrmophis thomensis of West Africa (its other relations live 

 in East Africa, South and Central America) is also viviparous. 



