478 GEORGE H. CARPENTER. 
The Maxille of Polyxenus., 
I am now glad to be able to show that Polyxenus—an 
undoubted Diplopod—closely resembles the lowest Insecta 
and the Symphyla in the structure of its mouth-organs. 
The gnathochilarium of a millipede is generally believed, on 
embryological grounds, to consist of one pair only of maxille, 
although its structure strongly suggests the presence of two 
pairs, the anterior of which has come—as in Scolopendrella 
—to le externally to the hinder. Latzel, in his description 
(21) of Polyxenus, states that the nature of its gnathochi- 
larium is doubtful, a pair of reduced appendages with con- 
spicuous palps being evident, and in front of these a flat 
plate, apparently comparable to the hypopharynx of ordinary 
millipedes. 
The collection of Diplopoda in the Dublin Museum con- 
tains numerous specimens of Polyxenus lagurus, collected 
many years ago by the late Robert Templeton; my friend 
Dr. R. F. Scharff has kindly given me facilities for examining 
this material. By dissecting heads, partially cleared in 
potash, under a compound erecting microscope, with fine 
needles, one can determine accurately the arrangement of 
the parts. The palps, very imperfectly segmented, rugose, 
and spiny (figs. 1, 4 ma. p.), and the rounded lobes, also 
rugose and spiny (fig. 1, ma. lo.), each partially divided into 
a larger posterior and a smaller anterior section (figs. 4, 5, 
me. lo.), are borne upon basal sclerites (figs. 1, 4, 5, ma.) 
which are attached proximally to the ventral head-skeleton, 
and fused distally and centrally with the labium (see figs. 
1-4, la). Otherwise, however, they lie within (v. e. anteriorly 
to) the labium. ‘This latter organ consists of a narrow, 
transverse basal membrane (fig. 1, /a’) attached to the ventral 
head-skeleton, and bearing a pair of broadly trapezoidal 
sclerites (fig. 1, Ja) which meet in a central, longitudinal 
suture. This labium clearly corresponds with the internal 
stipites of the typical diplopodan gnathochilarium, and 
represents, as I believe, a reduced second pair of maxille. 
