620 THE AMERICAN NATURALIST. | [Vor. XXXVI. 
a nearly vertical line toward the dorsal side, where, after making 
a turn at right angles, it joins the cesophagus (Fig. 10). 
In 4, Fig. 6, is shown a cross section of the sucking organ 
(pharynx) after the point of juncture of the two tubes into one. 
On the anterior and posterior side it is 
heavily chitinized, these surfaces, together 
with the tendons on the anterior side, 
being the points of attachment for two 
pairs of strong muscle bands. The 
remaining portion of the wall of this 
sucking pharynx is of thin membrane. 
At the contraction of the muscles sur- 
rounding it, the cavity within is increased 
many times the size it has when the mus- 
cles are relaxed. This mechanical con- 
trivance forms a very effective pump for 
drawing the juices of the sponge tissue 
Fic. 7.—Antemz. a,adult, through the sucking tubes into the 
x 18; 4, larval, x 36. 
cesophagus. 
The larval antenna has in most cases sixteen joints, those 
beyond the third being usually of equal length. The third is 
equal in thickness to the seg- 
ments just mentioned, but equals 
in length the next three or four 
segments. The second is equal 
to the fourth in length, but is 
twice as thick. The first equals 
the second in thickness, but is 
only half as long. The eleventh 
is frequently somewhat shorter 
and the twelfth, somewhat longer 
than the fourth, but they are both 
equal to it in thickness. The 
thirteenth is curiously ovate, and 
the three terminal ones are very slender and bear one or two 
small spines. At the base of the ovate joint is a much longer 
spine. In Fig. 7 the antenna of larva and adult are shown 
comparatively, but under different magnification. 


Fie. 8.— Legs. 4, larval, x 463 
b, adult, x 22; c, enlarged inner 
view of foot. 
