DEVELOPMENT OF THE COMMON FROG. 109 



sides of the pond, and have retired to the bottom ■ none 



are anywhere to be seen. 



68. The tadpoles having returned to the dead leaves at 



the shallow part, a number of them were taken out; and 



two of them were selected, which differed most in size and 



in the development of the hind legs. Outline drawings, 



natural size, were made of them. 



68 (2) . The intestine of the smaller specimen was divided 



close to the vent and drawn out to show its length, which 

 was about three and a half times the length of the body. 

 A drawing, natural size, was made of it. 



69. An enlarged drawing was made of the left side of a 

 tadpole, showing the opening from the gill-chamber. A 

 dull-white band in the skin was seen to pass obliquely 

 from the opening forwards and downwards under the front 

 of the chest, marking the passage from the gill-chamber 

 to the external opening, which was at the end of a short, 

 conical, projecting tube, as represented in this and in all 

 the other drawings of this part. 



Plate X,VII. 

 69 (2). A drawing was made of the mouth of the tad- 

 pole of which the enlarged outline is given on Plate XVI. 

 69. There were on the upper lip four lines of small brown 

 teeth set in frames like combs : the outermost extended 

 from side to side ; the others were in pairs, each shorter 

 than the one before it, the inner border of the lip, where 

 it formed the opening of the mouth, being of an arched 

 shape. On the lower lip were four lines of combs, the 

 teeth of which were longer than those of the upper lip : 

 the outermost consisted of two parts nearly meeting in 

 the middle; the next and next but one were complete from 

 side to side ; and the innermost was formed of two short 

 combs not meeting the middle. 



