ii OVIPOSITION NURSING 55 



B. Amplexus of lengthy duration and in the water. 



a. The male, distinguished by a greater development of the fore- 

 limbs, which are armed with temporary excrescences, clasps the 

 female in the axillary region with the fore-limbs : Triton waltli. 



b. The male, distinguished by a greater development of the hind- 

 limbs and a prehensile tail, clasps the female in the lumbar and 

 caudal regions : The Euproctus-group of newts : Triton asper, 

 T. rusconii, and T. montanns. 



The act of fecundation of most of the other kinds of Urodela, 

 notably Cryptdbranchus, Ampliiuma, Proteus, has not yet been 

 observed. 



Embracing of the two sexes is the universal rule with the 

 Anura, the male creeping on to the back of the female and 

 clasping her firmly with the arms and hands either in the 

 inguinal region, higher up, or under the armpits. See the 

 numerous statements in the systematic part. This often ex- 

 tremely forcible, pressing embrace seems to be necessary, although 

 the females can deposit the eggs without the help of the male, 

 but in such cases the expulsion takes place at irregular intervals 

 instead of at one time. When the eggs appear at last, and this 

 happens in many species many hours, or even some days, after 

 the beginning of the embrace, the male voids the contents of 

 its seminal vesicles over them. Fertilisation is consequently 

 external, with the possible exception of Pipa, q.v. p. 152. 



Deposition of the eggs and nursing habits. The majority 

 of the Amphibia are oviparous, but some Apoda and Urodela 

 are viviparous. It is unnecessary to call the latter condition 

 ovo-viviparous, since this is really a distinction without a 

 difference. 



Viviparous forms : amongst Urodela ; Salamandra maculosa, 

 the young burst the egg-membrane in the act of being born, and 

 are provided with long gills ; S. atra, the young undergo their 

 whole development and metamorphosis within the uterus (see 

 p. 119); Spelerpes fuscus, the young are likewise born in the 

 perfect condition : amongst Apoda ; Typhlonectes compressicauda 

 and Dermophis thomensis. 



The oviparous Apoda, at least Ichthyophis and Hypogeophis, 

 and a few of the Urodela, as Desmognathus and Amphiuma, take 

 care of their eggs by coiling themselves around them in a hole 

 underground. 



Nursing habits are very common amongst the Anura. 



