100 THE ZOOLOGIST. 



bivalve — some species of Sphcerium or Pisidium. One of these 

 molluscs had closed its valves upon the inner finger of one of the 

 fore limbs, while another held tightly by the middle toe of one 

 of the hind feet. Yet, seriously impeded as its movements must 

 have been, the Toad was still able to swim after a sorry fashion. 



At the same time and place I noticed a very small male which 

 had only one hind leg ; all the bones of the corresponding 

 limb were apparently wanting, but the foot was present, though 

 smaller than its fellow, and attached to the trunk by the 

 skin alone. 



Our Common Toad has a habit of swimming with the hind 

 legs alone, keeping the fore legs or arms pressed against the 

 sides. The Fire-bellied Frog (Bombinator igneus) often adopts 

 the same method. 



The casting of the skin frequently takes place soon after the 

 arrival of these batrachians at their breeding places in early 

 spring, but whether the operation is always performed at this 

 season I do not know. In the year 1882, I noticed two females 

 in the water casting their skin on March 20th ; and in the 

 following year met with another female thus engaged in April. 

 I have never been so fortunate as to detect a male in the act. 



The tadpoles of both Frogs and Toads are excellent scaven- 

 gers, and the vast numbers which literally blacken the water of 

 many ponds and ditches must be of great use in keeping it pure 

 and wholesome. Decaying matter of almost any sort, animal or 

 vegetable, is greedily devoured by them. I have seen them 

 feeding on the dead bodies of Toads (possibly their own parents), 

 Sticklebacks, and even of tadpoles, as well as on cow-dung which 

 had dropped into the water ; also on the soft parts of submerged 

 and decaying leaves of trees and various plants, the veins being 

 left untouched. 



Instead of roaming about, as it were, at random in search 

 of food, some degree of unity and method may sometimes be 

 observed in the movements of these vast armies of tadpoles. In 

 the marsh ditches, where they abound, it is not unusual to find 

 two dense streams of them steadily travelling close alongside 

 one another, but in opposite directions ; an " up" and a " down" 

 line, in fact, seems to be strictly maintained and adhered to, in 

 order to prevent confusion. I once saw a number of tadpoles, 



