Allen.] 196 [Decemb«2, 



especially at night, they are frequently seen on their passage from 

 one pond or brook to another, or on short foraging excursions. 



8. Rana palustris Lt-Conte. (Storer's Rep., p. 238.) INIarsh 

 Frog. Pickerel Frog. Abundant. Generally associated with the 

 preceding, Avhlch it closely resembles in habits. 



9. Rana haleeina Kalm. (Stoi-er's Rep., p. 237.) Leopard 

 Frog. Common. Much less abvmdant than either of the preceding 

 Ranee. In summer it is very generally found in fields, often re- 

 mote from water; its favorite haunts are the moist, thick grass of 

 meadows. 



10. Rana sylvatica LeConte. (Storer's Rep., p. 239.) Wood 

 Frog. Common. At Springfield it is about as numerous as the last, 

 but in the vicinity of Cambridge one of the most abundant Ranee, 

 especially at spawning time. It is seldom seen about the water after 

 the breeding season ; often met with in summer in much the same sit- 

 uations as R. haleeina, but more commonly in the woods, where I 

 have seen it in November, as well as in March. I feel quite con- 

 fident that this species, as well as the toads (-Bm/o and Scaphiopus), 

 Hyla Pickeringii and the other Hylce, do not always resort to ponds 

 or marshes to hibernate, though such may be the general habit of 

 most of them. I have seen individuals of this species in the woods 

 on their way to ponds before the snow-banks were entirely melted, 

 having hibernated, I have no doubt, beneath the leaves. 



On their first appearance in spring their color is generally much 

 darker than later in the season, individuals being sometimes seen that 

 are nearly black, or of an intensely dark brown, on the dorsal sur- 

 face. Exposed to the light, however, they soon become paler, some- 

 times changing greatly in a few hours. This dark color is common to 

 both sexes, and is not peculiar to the males, as some have supposed. 

 At any season different individuals are found to vary greatly in 

 color; and from observing specimens in captivity, I have found that 

 the same individual differs very consideral)ly in depth of color in the 

 course of a few days, or even hours. The same variation occurs, 

 perhaps even more markedly, in Hijki Pickerinffil and Hyla versicolor. 

 In the latter species the variation seems fully under the will of the 

 animal, the change from light to dark being sometimes made so sud- 

 denly as to be distinctly visible. From experiments made on this 

 animal, I have found that the change is not at all dependent upon 

 its surroundings, all the variations in color, which consist merely in its 

 intensity, ranging from dark to light (light bluish-gray to quite 



