RANA. 



339 



the mud under water, in company with the common 

 frog, where the two species co- exist. 



Eggs. — Vitelline sphere measuring 2 to 2^ mm. (up 

 to 3 according to Peracca), blackish-brown in the upper 



Fig. 124. 





half, whitish in the lower; mucilaginous envelop, 

 when swollen out, measuring 9 to 12 mm. The esT^s 

 form a single lump, smaller as a rule than in B. tern- 

 poraria, and do not float. According to Heron-Rover 

 their number varies between 669 and 1200. I have 

 myself counted 1188 and 1415 in broods from Turin. 

 The embryo, on leaving the egg, is of a paler brown 

 than in B. temporaria, and its external gills are much 

 less developed and unpigmented. 



Tadpole (PI. Ill, fig. 7). — In general form similar to 

 B. esculenta, but snout rather shorter, the nostrils being 

 equidistant from the eyes and the end of the snout, 

 and spiraculum considerably nearer the posterior than 

 the anterior extremity of the body. Interocular space 

 twice as great as the distance between the nostrils. 

 Tail twice to twice and a half as long as the body, 

 pointed and attenuate or submucronate at the end, its 

 depth about twice and two thirds in its length ; upper 



