Packard.] 320 [Maya, 
RU)>])orted b}' a large, curved, cliitiiious;, ii)coin])lete i-iiig (tlie 
lioinologue of tlie Jcieferkapsel of Brauer) enclosing the base of 
tlie iirst niaxillary joint, the lower jiortion of the ring expanded 
triangularly, and sending out laterally a slender curved hook. 
From this apparatus two parallel, long, slender, chitinous rods 
pass backward, ending near the middle of the head, and forming 
the support of the muscles extending and retracting the maxillae. 
The second maxillae (Figs. 3-5, mx'-) have undergone much 
reduction, and are very minute. They are united at the base 
as usual to form the labiiim, and each division ends in three 
slender spinules. In their minute size, rudimentary shape, the 
entire labium ending in six spinules or slender teeth, the 2d 
maxillae more closely resemble those of certain eucephalous 
dipterous larvae than those of the Coleoptera or any other group. 
The caudal stylets (Figs. 1, 3, 0) are strong, recurved, chitinous 
structures which prop up the body of the larva in creeping or 
wriggling over the surface, and remind us of similar props in the 
larvae of the scavenger Coleoptera. We know of no similar 
structure in dipterous larvae. They are evidently adaptational 
outgrowths and of little morphological or taxonomic significance. 
CoMrAKISON OF THE LaRVA WITH THOSE OF THE DiPTERA. 
The larvae of the Pulicidae have been usually likened to those 
of the eucephalous Diptera, together with those of the Myceto- 
philidne, rather than to those of any other order, and yet in some 
respects they are nearly as much like those of certain Coleoptera 
as those of the Diptera. 
External anatomy. — In comparing the head of a Pulex larva 
with that of a G-yrinus it will be seen that the under side of the 
head of the former is very similar to that of Gyrinus and other 
coleopterous larvae in the jjerfection, and especially in the definite 
larger scutellate mental and gular region, which extends poste- 
riorly to near the hinder edge, as shown in Fig. 6, B, mt. This 
region is not apparently developed in the dipterous larvae, owing 
to the extensive modification of the head. In other respects there 
is no special resemblance between the larv.ie of the Pulicidiie and 
those of Coleoptera. 
