128 E VOL UTION AND DISEASE. 



Dr. Tuckerman l has placed on record an account of 

 such a specimen. The subject was a frog (Rana 

 palustris) ; it was blown from out a crevice in a ledge 

 of mica schist during some blasting operations. The 

 crevice was twelve feet below the surface and measured 

 only a few lines at its widest point ; flowing into the 



FIG. 72. A Chick with supernumerary legs. 



crevice was a small stream of running water, which 

 undoubtedly conveyed either the eggs, or the frogs in 

 the larval stage, to the interior of the rock, as the 

 breach in the ledge was much too small even to admit 

 the passage of a very young frog. This frog had, as 



1 Journal of Anatomy and Physiology, vol. xx. p. 516. 



