160 PROCEEDINGS: BOSTON SOCIETY NATURAL HISTORY. 
cles. It would appear that the pharynx of Anopheles has some¬ 
what more sharply marked angles than the pharynx of Culex and 
may therefore be a more effectual pump. The muscles are the 
same as in Culex: hypopharyngeals from the walls and crest of the 
pharynx, five pairs of elevators of the palate with the same relations 
to the soft and posterior hard palates, epipharyngeals from the alae 
of the clypeus, lateral pharyngeals, ascending pharyngeals, and 
valvulars. The ascending pharyngeals arise from the median inter¬ 
nal crest alone and not from crest and vertex of the head as is the 
case with Culex. 
The antlia of the female mosquito is pyriform with the bulb 
behind the nerve-collar. The chitinous intima. which lines this part 
of the alimentary canal is so modified that it is convenient to speak 
as if it were composed of three racquet-shaped plates, one dorsal, 
the others ventro-lateral in position. 
The borders of the plates are reflected and a thin band of chitin 
is included between each adjacent pair of plates. The plates can 
spring inward until they almost obliterate the lumen of the canal 
(pi. 13, fig. 12) or be drawn back by muscles until the lumen of 
the bulb has a nearly circular section. As the plates terminate 
posteriorly they are clothed by a dense coat of fine bristles and 
this development continues for 10 /xor more on the thin intima of 
the esophagus. The postneural bulb is the active part of the pump. 
Here the dorsal plate receives two large dorsal dilator muscles from 
the vertex of the head. These muscles are compressed and in an 
average female of Culex stimulans their greatest diameter was 60 /x, 
the lesser diameter 31 /x. In a male of the same s’ze the corre¬ 
sponding diameters were 60 /x and 15 /x. These muscles correspond 
to the “musculi superiores antliae ” (Meinert, ’ 81 ) and to the “supe¬ 
rior pumping muscles” (Christophers, : 01 ), “post dorsal dilators” 
(Nuttall and Shipley, : 01 -: 03 ). Either lateral plate receives five 
lateral dilator muscles from the sides of the head. These muscles 
trend forward and upward to their insertions and are compressed. 
In an average female of C. stimulans the greatest diameter of the 
first to the most posterior muscle was 54, 56, 72, 54, and 44 /x 
respectively and the lesser diameter 27, 20, 37, 18, and 20 /x. The 
total cross section of the female’s muscles is nearlv twice that of the 
muscles of the male. The lateral dilators have been described as 
“musculi inferiores antliae ” (Meinert, ’ 81 ), “lateral pumping mus- 
