2 . PHYTOPHAGA. 
Old World. Many of the Central-American species are large and conspicuous, and © 
being abundant in the various localities in which they occur, are doubtless (as 
Mr. Wallace states) protected from the attacks of birds and other enemies by the pos- 
session of some noxious smell or taste. The coloration and markings of the different 
species are (with some remarkable exceptions) constant, and show little tendency to 
variation; in some groups a uniform pattern runs, with but little change, through a 
series of specific forms, in many cases belonging to separate genera. 
It will be seen that I have, as formerly, used the modifications in size and shape of 
the labium in the arrangement of the generic groups. 
The labium is large and exposed, and is thus readily examined a setu by an ordinary 
microscope without risk of injury to the specimens ; it is divided into two segments, 
the mentum and ligula. 
I. The mentum, or basal segment, is connected by its lower edge with the margin of 
the skull, and is attached on either side to the maxilla; at first small, and forming a 
single piece with the ligula, it gradually increases in size until ultimately it forms the 
larger portion of the whole labium. 
II. The ligula: this segment is placed in one division of the family at the apex, in 
the other on the dorsal surface of the mentum; it consists of two subsegments, the 
basilar and apical, which are separated from each other by well-defined sutural lines ; 
the basilar portion, from the anterior surface of which spring the labial palpi, varies 
greatly in size and shape; in the earlier genera of the family it is large and prominent, 
but gradually dwindles away in exact ratio to the increase of the mentum, until at 
length (Chondrina) it, together with its appendages, the labial palpi, entirely disappears ; 
the apical subsegment is corneous, and sometimes placed at the apex, sometimes on the 
dorsal surface of the preceding subsegment ; in the latter case it is hidden from view. 
I should not have thought it necessary to make these remarks had not the late 
Dr. Chapuis (Gen. Col. t. xi. p. 252) questioned the accuracy of my nomenclature of 
these parts, and in so doing fallen into a singular error, which, if not corrected, might 
tend to mislead future students of the group. 
After having stated (J. c. p. 255) that the maxille are attached, one on either side, to 
the base of the mentum, he proceeds to say that there is often an additional segment, 
the sous-menton, placed between the true mentum and the margin of the head, referring 
to Cat. Hisp. tab. i. A a, and fig. 8 f as illustrating the part in question. He thus divides 
the labium into three segments :—1, a basal one, or sous-menton; 2, an inter-mediate,or 
menton; and 3, the languette, which, according to his statement, carries the labial palpi. 
Had he, however, examined the parts in nature, for example, in Alurnus, to which 
figure he refers, he would have seen that the maxille are attached -to the short trans- 
verse segment (his sous-menton), showing it, even according to his own views, to be the 
true mentum; had he carried his investigations further, and examined the second 
segment, which he terms the menton, he would have found that the labial palpi spring, 
