162 REVIEW OF AMERICAN BIRDS. [PART I. 
tongue, in this instance, is much longer, and narrower than usual ; 
bifid for more than one-third its length, and fringed at the end, much 
as in Certhiola. It differs from other Sylvicolide, also, in having 
the sides of the tongue, from the middle, folded over and down on 
the upper surface, though not adherent, nor does the lap extend quite 
to the tip. This characteristic of the fold, and the absence of a ver- 
tical fimbriated lamina adherent to the inner edge of the horizontal 
bifurcation of the tongue, appears essentially peculiar to this bird. 
This difference of the tongue in “Dendroica tigrina” is so funda- 
mentally great, as compared with all other Sylvicolide, that were 
the other characteristics of seasonal changes of plumage, geographi- 
eal distribution and migration, pattern of coloration, etc. more 
similar, it would almost warrant our removing it to another family, 
if not making it the type of a new one. As it is, it becomes neces- 
sary to establish a new genus (Perissoglossa) for it, ieft now among 
the Sylvicolide, but perhaps hereafter to be transferred elsewhere. 
The following diagrams of tongues of some of the Cerebide, 
Sylvicolidx, and Vireonide have been drawn, at my request, on 
wood under the microscope by Dr. W. Stimpson; to whom, also, I 
am indebted for the accompanying remarkst relative to their charac- 
' «The tongues are all fissured, or bifid at the extremity, by a slit of variable 
depth; one-third the length of the tongue in Glossiptila, Certhiola, and Perisso- 
glossa, but only one-sixth its length in Vireo; in the others averaging about 
one-fourth its length. By this slit two forks are formed, which are depressed, 
corneous, laminiform, and incised along the extremity and outer edge by 
more or less numerous fissures which form a fringe of flattened sete con- 
tiguous at base, but becoming narrowed and thus separately projecting in the 
same plane at their extremities. The lateral sete are transverse or even 
curved backward in Gilossiptila, but point obliquely forward in all the other 
species. 
‘“‘The inner edge of the fork is always much thicker than the external 
laminar expansion, and generally ends in a sharp spine, far stronger than the 
proximate sete. But in Glossiptila and Certhiola this inner edge is itself 
expanded upward into a narrow lamina, which is either in a plane perpen- 
dicular to the lateral expansion or folded over toward it, and this second 
lamina is also divided into oblique or longitudinal sete toward its extremity. 
At the extremity of the fork the two lamine are confluent, continuous, and 
regularly fimbriated around the curve. 
“In Certhiola and Perissoglossa the sides of the tongue at the base of the 
forks are folded over and inward, but in Certhiola the folds are soldered down 
to the base and inner edge of the forks; while in Perissoglossa they are not 
soldered, but open outward again anteriorly before the edges become fimbri- 
ated, so that the extremity of this tongue (Perissoglossa) is broad, and the 
sete nearly longitudinal. 
