796 The American Naturalist. [September, 
the evening to secure their insect food. They progress by hops, and 
only walk on very rare occasions." 
Of Rana virescens ihalecind) it is said : 
" This species is especially an inhabitant of swamps. It is found in 
great numbers in those that border the large creeks and rivers of the 
Atlantic coast, and is comparatively rare inland* where it gives place 
to other species. With the Acris gryllus, it is the first species heard in 
Spring, and although its voice is not loud, the noise produced by 
thousands of them is deafening when heard close at hand, and is 
transmitted through the atmosphere for many miles. It may be imi- 
tated by the syllables 'chock, chock, chock.' As a harbinger of 
Spring it is always welcome." 
The habits of the Hyla pickeringii are thus described : 
" This, our most abundant Eastern species [of Hyla], is much more 
generally known by its voice than appearance. After the rattling of 
the Acris gryllus in the marshes and river banks in the lowlands is 
fairly under way, during the first bright days of Spring, the shrill cry 
or whistle of this little creature begins to enliven the colder swamps 
and meadows of the hill country. Different individuals answer each 
other with differently toned voices of a single note. This is exceed- 
ingly shrill and loud ; the muscular force employed in expelling the 
air from the lungs seems to collapse the animal's sides till they nearly 
meet, while the gular sac is distended with each expulsion to half the 
size of the head and body together. They are chiefly noisy in the 
end of the afternoon, but in shady situations or on dark days may be 
heard through the morning and noon. When the breeding season is 
over they may be still found, but with difficulty, among fallen leaves 
in low places, where their color admirably adapts them for conceal- 
ment, or in cellars, or on the ground in the woods. Not till the near 
approach of Autumn do we have evidence of their a.scent into the 
trees. Then, when the wind is casting the first frosted leaves to the 
ground, a whistle, weaker than the Spring cry, is heard, repeated at 
intervals during the day, from one i)art of the forest to another, bear- 
ing considerable resemblance to the note of the purple finch {Carpo- 
dacits purpureiis'), uttered as it is while flying. These voices are heard 
during the same season ; that of the Hyla is distinguishable as slightly 
Southern flight. These are the latest sounds of Autumn, and soon 
disappear before the steady advance of the ice king." 
A bibliography, from which we notice the omission of some titles, 
and a full index to both plates and text close the book. 
