The number of eggs or young of one brood varies much according to the species, and also according to the age of the mother, large females usually producing a higher number and of a larger size than smaller specimens of the same species. Our European _Zamenis_, _Coluber_, and _Coronella_ produce only 2 to 15; our _Tropidonotus_, 15 to 48; our Vipers, 3 to 22. Among exotics we may mention, as the most prolific, _Bitis nasicornis_, up to 47 young; _Tropidonotus fasciatus_, _Abastor erythrogrammus_, and _Farancia abacura_, 50; _Lachesis lanceolatus_, 60; _Vipera russelli_, 63; _Boa constrictor_, 64; _Tropidonotus ordinatus_, 78; _Pseudaspis cana_, 80; _Python molurus_, nearly 100 eggs. The eggs are deposited in holes without any sort of nest, under moss or decomposing leaves, in accumulations of saw-dust, or in manure-heaps. In many cases it has been observed that the female remains for some time with her eggs or young, and in the large Pythons a sort of incubation takes place, the female remaining coiled in a spiral over the mass of eggs for six to eight weeks; an increase of several degrees in her temperature at that period has been ascertained by experiments conducted with every possible care, a remarkable fact in the case of a so-called "cold-blooded" animal. The numerous reports of young snakes seeking refuge in their mother's gullet have not been substantiated by satisfactory scientific evidence, and, although it is perhaps wise to say that the question remains an open one, it may be mentioned that, in Europe at least, trained observers who have devoted special attention to the habits of Vipers, in districts where these reptiles are exceedingly abundant, have never come across an instance of the form of maternal solicitude with which these snakes in particular have been credited. Not a single reported case of a female snake swallowing her young for protection rests on satisfactory evidence.