THE ADDER. 



155 



larger and quite round, the embryo being seen through 

 the covering membrane lying on the egg surface. The 

 embryos were 3| inches long, and, except in size, were 

 much like those of July 10. 



A dissection a fortnight later shows still more rapid 

 progress, and by August 13 the embryos look like 

 young adders for the first time. 

 Even through the egg-membrane 

 the markings could be distin- 

 guished, the e^ being the one 

 reproduced here. The embryos 

 in this adder were again ten in 

 number, and it was surprising 

 on measuring them to find they 

 were 5 inches in length. I 

 photographed three of them, 



with a scale of inches marked on the dish (fig. 37), 

 which gives a very good idea of the size and general 

 appearance. 



The anterior abdominal wall was now completely 

 closed. The colour of the belly surface was still 

 whitish, but the division where each scale was to 

 appear w T as evident. The colour shaded off' into grey 

 on the back, and the markings were distinct, the zig- 

 zag line and the extra line of patches opposite each 

 point of the zigzag both quite plainly visible. 



There is one very interesting detail in connection 

 with the development of the markings which is seen 

 at this stage. It is this. At the posterior part of the 



Fig. 36.— Egg of Adder. 



