54 AMPHIBIA 



(luring one season is not only difficult to calculate, but it varies 

 individually, old females laying more than young specimens. 

 Moreover, some kinds, e.g. the Discoglossidae, spawn several times 

 in one year. Alytes, Rhinodenna, Hylodcs, Ilhaco^jhorus, Fipa, 

 in fact those kinds which are remarkalile for special nursing 

 habits, lay only a few dozen eggs at a time. Ilj/Ia arhorca pro- 

 duces up to 1000, Bana temporaria about 3000, Bufo vulgaris 

 averages 5000, Bufo viridis and Ra7ia escideuta up to 10,000 

 and more. T. H. Morgan ^ has ol)served a Bvfo lentiginosus 

 which laid 28,000 eggs within ten hours ! The number of eggs 

 produced by the Apoda and Urodela is comparatively moderate, in 

 the average a few dozen, Amldy stoma alone laying about 1000. 



The eggs possess a gelatinous mantle of variable thickness and 

 consistency. In Aniphiuma they are strung together like the 

 beads of a rosary, and the envelope hardens into a kind of shell. 

 Many Xewts and some Anura fasten their eggs singly on to 

 plants and other objects in the water, with or without threads of 

 stiffening mucus. In many Anura, e.g. Bufonidae, they pass out 

 as closely-set strings of beads, one string out of each oviduct ; in 

 others, e.g. Eanidae, they are disconnected, and form large, lumpy 

 masses, especially when the gelatinous mantle swells up in the 

 water. The use of this mantle seems to be chiefly the protection 

 of the growing embryo, which in many species, when hatched out 

 of the egg proper, drops into and remains for some time in the 

 softened jelly. Possibly the latter affords some nutriment to the 

 early larva. 



Concerning the mode of fecundation it is to be remarked 

 that copulation proper takes place only in the Apoda. For the 

 Urodela Boulenger " has given the following summary. In no 

 case does actual copulation take place. The male deposits the 

 spermatophores which it is the office of the female to secure : — 



I. Nil aiuplexus, but a lengthy courtship in tlie' water; the male is more 

 lu'illiantly coloured than the female, and ornamented with dorsal and 

 caudal crests, or other apjiendages : Triton., cf. also systematic jjart. 

 II. Amplexus takes place ; there are no marked sexual difterences in colour 

 and no ornamental dermal apjjendages. 

 A. Amplexus of short duration, partly on land, but deposition of the 

 sperma in the water. No accessory sexual characters : Terrestrial 

 Salamanders, namely Salamandra, Chioglossa, Salaviandrina. Hpel- 

 erpes breeds in damj) caves without water. 



^ Amer. Naticral, xxv. 1891, p. 753. - Zool. Jahrb. S'yst. vi. 1892, p. 447. 



