OVIPOSITION 87 



The yolk entirely fills the eggshell ; there is no 

 albumen, or, if any exists, it is so much reduced as to 

 easily escape observation. The eggshell in oviparous 

 species contains a small amount of lime, and is 

 not hard, but tough and parchment-like, white or 

 yellowish; it is usually smooth, but in Pythons its 

 surface is studded with minute pores, and in the 

 American Zamenis constrictor it is rough, as if 

 sprinkled over with loose grains of salt. The shape 

 varies from a short oval to a long ellipse. It has 

 been observed in some snakes that the eggs, on 

 leaving the cloaca, are of an elongate shape, sugges- 

 tive of a short cigar, and immediately after assume 

 a more oval form. After they have been laid, the 

 eggs absorb moisture and thus increase in size, espe- 

 cially in width ; eggs which are at first twice as long 

 as broad may be almost globular just before the birth 

 of the young. 



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 erythrogr animus, and Farancia abacura, 50; 

 Lachesis lanceolatus, 60 ; Vipera russelli, 63 ; Boa con- 



