338 



Zoological Society ;— 



and Western Africa ; and also to retain the opinion that I have pub- 

 lished, that the specimens brought by Mr. Walker from Lagos are 

 probably of a distinct form. I will not take on myself to deny the 

 possibility of their being the larya. of Dacti/lethra, as the larva of that 

 genus and the adult form of Silurana are unknown ; but even if it is 

 proved hereafter that they are only the larva of Bactylethra, I think 

 that it is better for the present to keep them separate, until the 

 change from one state to the other has been observed and recorded ; 

 at all events, the description and observation of the larva is an 

 important addition to the history of the genus. 



It would be a remarkable change, if the large beard that is placed 

 at the angle of the mouth in one genus should turn into the minute 

 beard on the lower edge of the orbit, far above and in front of the 

 angle of the mouth, in the other ; yet 1 am assured by an experienced 

 herpetologist that he believes this change does take place, and that 

 it is only consistent with what is to be observed in the transfor- 

 mation of other Batrachians. No such changes have occurred to 

 me. There is no doubt that the beard at the angle of the mouth is 

 much longer and more slender in the young larva than it is in the 

 oldest specimen we yet possess of the genus Silurana. But while 

 the beard diminishes in length, it increases considerably in thick- 

 ness, showing no inclination, to disappear, and does not at all alter 

 its place in any of the specimens I have observed either in the British 

 Museum or at Liverpool. 



The least-developed fish-formed specimen (fig. 1) is about 2\ inches 

 long, and has only the hinder pair of legs developed. The legs are 



short and weak ; and the toes are short and of nekrly equal length, 

 but with the three black claws well developed. The head is de- 

 pressed, very broad, and flat above, and shelving to near the back 



