92 



APODA 



outer gills. The larvae frequently come up to the surface to 

 breathe. The eyes are large and clearly visible, but the tentacles 

 are still undeveloped. The epidermal sense-organs are numerous, 

 and appear as white spots in the grey skin ; about fifty extend 

 from the gill-opening to the tip of the tail. 



Ichthyophis seems to live a long time in the larval state. At 

 last the gill-clefts close, the tail-fin disappears, and the tentacles 

 come to the surface. The whole skin assumes a totally new 

 structure, and the fish-like larva turns into a burrowing, sub- 

 terranean creature so terrestrial that it gets drowned when made 

 to remain in the water. 



Hy2}ogeo]}]i,is. — According to A. Brauer^ three species of 

 (Joecilians are found in the Seychelles : Cryptofsophis multipili- 

 raf/us, which is rare, Hypogeophis rostratus and H. cdternans. 

 They live in moist ground, near the coast in swamps, higher up 

 in humus, under rotten trees and rocks, down to the depth of 

 one foot. In the island of Silhouette, Brauer found them in 

 brooks, at least during the dry season, from May to September. 

 The natives call them " vers de terre." They seem to propagate 

 during the greater part of the year, provided there is sufficient 

 moisture. The female coils round the eggs, which vary from 

 half a dozen to thirty in number, those of IT. rostratus measviring 

 7-8 mm., those of H. alternans only 4-5 mm. 



The embryos undergo their whole development in the egg. 

 Four pairs of gill-clefts break through, the first between the 

 hyoid and the first branchial arch, the fourth between the third 

 and fourth branchial arches. There appears also a spiracular 

 cleft between the quadrate and the hyoid arch ; this cleft is, 

 however, only developed dorsally, and persists for a shorter time. 

 The external gills appear at the same time as the clefts, upon 

 the first three branchial arches ; the third gill is the latest, and 

 remains in a vestigial condition covered up by the two others. 

 The gills, of which the second is the longest, are not (as stated 

 by the Sarasins) direct prolongations of the gill-arches, but they 

 begin as button -like growths upon the arches. They begin 

 to disappear with the absorption of the yolk, getting actually 

 smaller. In embryos of 6 cm. they are 6 mm. long, while in 

 embryos of 6.5 cm. they are reduced to 4.5 mm. in length. The 



^ " Beitrage zur Keniitniss del- Entwickluiigsgeschiclite und der Anatomic der 

 ymnopMonen," Zool. Jahrb. Anat. x. 1897, p. 389, and xii. 1899, p. 477. 



