DEVELOPEMENT OE KEPTILIA. 



637 



tfllirlc i)f a Viper at a more advanced period, showing the 

 yulk partially taken into tlie abdominal cavily. XLiii. 



448 



Tn figure 447, the vitel- 

 liclc of a Viper, at a more 

 advanced period, shows part 

 of the food-yolli entering 

 the abdominal cavity, at u: 

 the ductus vitello-intesti- 

 nalis, d, is reduced to a 

 thread : g is the intestine, 

 and /{ the kidney. 



Figure 448 shows the 

 body of a Viper just before 

 the period of extrication 

 Irora the egg - coverings ; 

 the parictcs of the abdomen 

 are partly removed to show 

 the vitellicle, b, which has 

 now become inclosed in 

 that cavity, with almost 

 complete obliteration of the 

 umbilical cicatrix : a, the 

 remains of amnios and al- 

 lantois : d, the much short- 

 ened ductus vitello-intesti- 

 nalis : g, the liver : ff, the 

 stomach : f, the duodenum: 

 n, the small intestine : the 

 other letters indicate the 

 same parts as in the pre- 

 ceding fio'ures. 



The gravid Viper is more 

 than usually sluggish, and 

 loves to bask in the hot 

 sunshine, turning her belly 

 as if to court the aid of the 

 extraneous warmth in ac- 

 celerating the internal in- 

 cubation of her eggs. 



Figure 449 shows the 

 Q(i-(y and embryo of the 

 jMonitor Lizard near the 

 iieriod of extrication: a is Body oi;a\-iperjustiieroreiti.siiatciicd. .\liii. 



tlie remnant of the food-yolk : b the amnion laid open to show the 

 embryo, d; its long tru'nk aud tail arc packed in spiral folds as 



