174 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
The elongation of the rostrum and the greater rigidity of its ventral 
surface require a different method of feeding from that employed by 
the Culex larva. Nuttall and Shipley state that the maxillae, man¬ 
dibles, and maxillary palp form the sides and floor of a cavity 
and that the flabellae “ are suddenly bent back into this space, the 
mandibles and maxillae moving forward to meet them and at the 
same time opening out; they are then as suddenly released and 
fly back to their original position. This movement.... is repeated 
with great rapidity, often some 180 times to the minute produc¬ 
ing a current sweeping in convergent curves towards the above 
mentioned cavity. From time to time the mandibles are approxi¬ 
mated and the stiff curved hairs of their upper edge are run 
through the brushes” (flabellae). That this may aid in removing 
food from the flabellae or “ brushes ” is shown by the further obser¬ 
vation that at intervals “the brushes disappear far into the mouth 
and are then slowly withdrawn, passing through the fine carding 
bristles on the inner face and anterior edge of the maxillae.” In 
Culex, according to my observations, the food is borne into the 
space formed by the mandibles and maxillae by a flickering motion 
of the expanded flabellas and retraction of these organs is infrequent. 
The carding of the flabellal setae is irregular in occurrence and can¬ 
not be observed in detail owing to the unfavorable position assumed 
by the feeding larva. This subordinate role for the flabellae is the 
main difference between the feeding habit of Culex and that of Ano¬ 
pheles. Sections indicate that Anopheles has a pharynx of the same 
general form and musculature as Culex, but of relatively inferior 
size. 
The esophagus (pi. 16, fig. 87, oes) has already been partly 
described. Its epithelium is flattened, especially toward the pos¬ 
terior end of the region. The chitinous intima is strong. Beneath 
the well developed circularis muscle-coat lies a longitudinal series 
of muscles, some of which emerge to form the lateral dilators of the 
esophagus. In the anterior part of the thorax the esophagus dips 
into the cardia as the esophageal valve. This valve is a deep cur¬ 
tain, thicker at base than at the free border. At the free border 
the space between the inner or direct face and the outer or reflected 
face is occupied by a blood sinus. Above, the space is filled by the 
circular fibers of the annular muscle (ann m). In young larvae the 
cells of the epithelium of the valve, except for a more columnar 
