IG THE ZOOLOGIST. 



individuals may be found indistinctly striped (not so frequently 

 as in England or Scotland) ; in others the excrescences on the 

 back are of an unusually dark brown tint. 



Towards the middle of April there are generally one or two 

 pairs in the fountain of the Schlossgarten, and other ponds near 

 Karlsruhe ; while large numbers congregate in more suitable 

 localities, such as that mentioned in the account of R. arvalis. 

 In the Black Forest I have seen them in pools of melting snow, 

 and it reflects credit on their constitution that they can survive a 

 prolonged immersion into water of the temperature of ice. But 

 most recently it has been shown that though frozen into solid 

 blocks, their ultimate recovery is ensured, if a slow and judicious 

 process of thawing be adopted. 



There is some fluctuation in the numbers of this species : in 

 some years it is comparatively rare, in others exceptionally 

 common. The latter was the case in 1887. A similar periodical 

 abundance has been recorded with other anurous batrachians, and 

 may be attributed in chief part to moist weather favouring the 

 development of the spawn at the critical moment. For whereas one 

 or two species display considerable forethought in selecting deep 

 water to deposit the spawn, others are most improvident in this 

 respect,* and content themselves with the first piece of water 

 that comes in their way. Hence large quantities of spawn must 

 perish annually, if a sudden drought sets in. 



Occasionally, in dry weather, batrachians will undertake 

 journeys across country in search of water. I have noticed this 

 principally with Bombinator bombinus, which, through establishing 

 itself in the most shallow and ephemeral puddles, is often obliged 

 to change residence. An emigration of Rana esculenta, on a more 

 wholesale scale, has lately been recorded, and, according to an 

 American journal, there can be witnessed, in Dakota, an annual 

 procession of frogs marching from the Red River (winter quarters) 

 to the prairies in summer, and back again in autumn. 



* It is not surprising to find this same lack of intuitive instinct with 

 birds. As an instance which has come under my own observation : — During 

 a spell of unusually fine weather, a number of Keed Warblers on the Kiver 

 Alb, near Karlsruhe, were tempted to build their nests long before the reeds 

 were of sufficient height. The consequence was that they were all destroyed 

 by a sudden flood, with one exception, where the bird heroically hatched its 

 brood, though the nest was covered with thick mud. In this and most cases 

 the catastrophe was unexpected; in others it appears as if repeated sad 

 experience will not effect the discontinuance of a habit formerly justiiio- 1 



