82 NATURAL HISTOHY 



LETTER XVII. 



TO THE SAME. 



DEAR SIR; Selbornk, June 18, I768. 



On \Vednesdat/]iist arrived your agreeable 

 letter of June the 10th. It gives me great 

 satisfaction to find that you pursue these 

 studies still with such vigour, and are in 

 such forwardness with regard to reptiles 

 and fishes. 



The reptiles, few as they are, I am not 

 acquainted with, so well as I could wish, 

 with regard to their natural history. There 

 is a degree of dubiousness and obscurity 

 attending the propagation of this class of 

 animals, something analogous to that of the 

 cryptogamia in the sexual system of plants : 

 and the case is the same with regard to 

 some of the fishes ; as the eel, &c. 



The method in which toads procreate 

 and bring forth seems to be very much in 

 the dark. Some authors say that they are 



