DEVELOPMENT OF THE COMMON FROG. 99 



the abdomen was marked by a slightly indented line cross- 

 ing from side to side. 



29 (May 1st). On examining a tadpole, the skin over 

 the eyes was seen to be transparent; but it contained nu- 

 merous minute black and gold-coloured spots, like those 

 in the skin of other parts of the body. It was continuous 

 over the eyes : and the eyes themselves were seen to move 

 beneath it ; each had a black pupil. The nostrils had a 

 small projecting fold in front of each. Rudiments of the 

 hind limbs were distinctly seen, in the form of a pair of 

 prominent papillae, one on each side of the vent at the 

 root of the tail. A drawing was made representing the 

 right side with one of the rudimentary limbs. A faint 

 trace of these had been previously seen, as a very slight 

 protuberance on each side, in the specimens examined and 

 drawn two days ago (27). 



29 (2). A drawing of a tadpole was made, the natural 

 size. 



29 (3). After being killed, it was examined under the 

 microscope and a drawing made, representing the upper 

 surface. The body, instead of being laterally compressed 

 and shaped like an ordinary fish, as it was in the earlier 

 stages, was now broad and depressed, and the head and 

 body were nearly equal in width. The chamber on each 

 side for the internal gills gave much of the apparent breadth 

 to the back of the head; and the greatly increased size of 

 the abdomen indicated rapid growth of its contained vis- 

 cera. The alimentary canal was certainly in action; for 

 fsecal matter was voided whilst the animal was under ex- 

 amination. 



Plate IX. 



30. Two tadpoles were drawn, the natural size. 

 One of them was killed and examined under the micro- 

 scope. It had a broad rounded body. On the upper sur- 



