206 AMPHIBIA 



species only. As in the Tailed Batrachians, the female is ferti- 

 lised internally, but, unlike them, a real copulation takes place, 

 the male being provided with an intromittent organ very much 

 like a penis, although morphologically representing only an 

 eversion of the cloacal walls. 



The breeding habits of IchtliyopJiis glutinosus, which 

 inhabits South-Eastern Asia, have been observed in Ceylon. 

 The female digs a hole close to the surface in damp ground 

 near water and deposits about a score of large yellow eggs, 

 measuring eight to ten millimetres in diameter. They are 

 strung together in the same way as those of Alytes and Cryp- 

 tobranchas, the connecting threads containing a very distinct 

 twisted cord of the vitelline membrane, corresponding to the 

 chalaza of birds' eggs, and form a bunch round which the 

 mother coils her snake-like body, protecting them against 

 enemies or possible desiccation until eclosion. (Plate XVI I., A.) 

 During this sort of incubation, the eggs enlarge, and within them 

 the larva develops, coiled over the spherical vitelline sphere, and 

 breathing by means of extremely long, delicately fringed ex- 

 ternal gills, three on each side. The gills shrivel and wither away 

 before eclosion, the larva leaving the egg in a gill-less condi- 

 tion, but with a hole on each side of the neck, such as persists 

 throughout life in Amphiiima y with small but well-developed 

 eyes, and with a short but very distinct tail bordered above 

 and below by a low fin. In this state it lives in the water like 

 an eel, until it reaches a considerable size (70 to 160 milli- 

 metres). Later the hole on the sides of the neck closes up, 

 the tail shortens and loses its fin-like crests, the eyes become 

 covered over by the skin and very indistinct, and the animal lives 

 on land for the rest of its existence. 



Like those of Alytes and DesmognatJius, the eggs were first 

 believed to be truly meroblastic, but more recent investigation 

 carried out on Hypogeophis render it probable that they 

 belong to a modified holoblastic type which closely ap- 

 proaches the meroblastic. 



In Hypogeophis, represented by two species in the Seychelles 

 the development is on the whole very similar to that of IchtJiy- 

 ophis, but the young does not pass through an aquatic larval 

 stage. It leaves the egg-capsule in the perfect condition and 

 at once leads a terrestrial existence like its parents. In accord- 



