DEVELOPEMENT OF REPTILIA. 



637 



447 



yolk partially taken into the abdominal cavity. XLIII. 



448 



In figure 447, the vitel- 

 licle of a Viper, at a more 

 advanced period, shows part 

 of the food-yolk entering 

 the abdominal cavity, at a : 

 the ductus vitello-intesti- 

 nalis, d, is reduced to a 

 thread : g is the intestine, 

 and k the kidney. 



Figure 448 shows the 

 body of a Viper just before 



tlie periOQ OI extrication yi tc iiiclc of a Viper at a more advanced period, showing the 



from the egg - coverings ; 

 the parietes 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 : #, the 

 remains of amnios and al- 

 lantois : d, the much short- 

 ened ductus vitello-intesti- 

 ualis : g, the liver : ff, the 

 stomach : f. the duodenum : 



t/ * 



?z, the small intestine : the 

 other letters indicate the 

 same parts as in the pre- 

 ceding figures. 



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 



o 



egg and embryo of the 

 Monitor Lizard near the 



period of extrication: a is Body of a Viper just before it is hatched. XLIII. 



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

 embryo, rf; its long trunk and tail are packed in spiral folds as 



71 



