552 The American Naturalist. [June, 
will be found. Lucas’ devotes much space to his proof that 
certain small, angulated processes projecting from below the 
eyes, and called rudimentary mandibles by some writers, are 
not such, but the remnants of the lower one of a pair of tuber- 
cles which, in the pupa, marked the limits of the genal surface 
with which the prominent mandibles of the pupa. articulated. 
The presence of these characteristic genal tubercles in all 
the species of Micropteryx which I have examined is worth 
mention (see figs. 3 and 5, g. t., plate XXV). That these tuber- 
cles are not mandibular remnants (if, indeed, it isto these pro- 
cesses to which Savigny, Brauer, et al. refer) is well shown by 
Micropteryx, in which both these genal tubercles and the true 
mandibles or mandibular remnants are present and obviously 
distinct. 
Passing now to the more familiarly known specialized Lepi- 
dopterous mouth-parts, a few commonly accepted beliefs de- 
mand brief reference. Moths and butterflies have been accre- 
dited with the possession of rudimentary mandibles asa general 
feature of the mouth-part conditions. The familiar statements 
and figures in entomological and zoological texts refer to cer- 
tain slight projections lying on either side of the so-called 
labrum, a minute median triangular sclerite, as rudimentary 
mandibles. The statements and occasionally the figures are 
traceable back tof Savigny’s enlightening study and explana- 
tion of the homologies of the insectean parts. This explana- 
tion was adopted by’ Burgess in his description of the anatomy 
of Danais archippus. In aê study of the sclerites of the head of 
this butterfly. I became convinced that the so-called rudi- 
mentary mandibles of Danais are not such, but are projections 
from the lateral extremities of the labrum, which also, to my 
mind, is a larger and other sclerite than the minute triangular 
5 Lucas (op. cit.) 
ê Savigny, Jule-Cesar, Theorie des organes de la bouche des Crustacés et des 
ects, 
nsecta, Linn., mem. 1-2, fase. 1, partie 1, of the Memoires sur les Anim- 
aux sans Vertebres, 1816, Paris. 
1 Burgess. Edw., tigen to the Anatomy of the Moth-weed Butterfly, 
` Danais archippus Fab., 1880, Boston. 
8 Author. The a of the Head of Danais archippus Fab., pp. 51-57, 
with 1 plate in the Kas. Univ. Quart. v. 2, no. 2. Oct., 1893. 
