Packard.! 
336 
[May 2, 
mx.p 
dilated at the distal end, whose lateral walls are at the end rolled 
up. In a ti-ansverse section through the base of the mouth-parts, 
his figure, whicli we copy (Fig. 21), the sides of the tube are 
continued down in the form of two 
chitinous bands turned down op- 
posite each other. These two 
bands in union with the two man- 
dibles (oberkiefern) surrouTid the 
canal (Fig. 21, a) which he re- 
gards as tlie true sucking tube. 
"But the tube which is formed 
by the unpaired organ itself serves 
for the exit of the secretions of 
the salivary glands, which are 
seen farther below. From each 
side of it arise two processes like 
those beneath. Each is rolled up 
longitudinally and fits into a cor- 
res])onding recess of the mandi- 
bles, thereby serving to keep the 
latter, with the unpaired organ, in 
a fixed position. At the end of 
the mouth-parts the lateral pro- 
cesses disappear. The inner side 
of the tube is traversed by dark 
cross-lines, which are only furrows. On the back of the un- 
paired organ, on the side opposite the sucking tube, is a high 
ridge (Fig. 21) which is to be seen only on the distal half of 
the organ. On this ridge near the end of the unpaired organ 
are two minute teeth, and from tliese passing obliquely to the 
base of the ridge are two transparent streaks which, according to 
Landois, arise from two small transparent canals." 
Similar structures occur in the unpaired organ of all known 
Siphonaptera (Sarcopsylla, Rhynchopsylla, Pulex) ; they only 
differ in the number and distribution of the teeth. On the inner 
side at the end of the organ described occur such protuberances 
and spinules as are found in the dog flea. 
In the appendix he thus refers to Kraepelin's paper whicli he 
had not seen when writing his article: "Kraeperm considers the 
unpaired piercing organ of the flea as the labrum (overlippe) for 
.jnx. p 
Fig. 21. Section thronijh the 
beak of Vermipsylla; A, through 
the base ; B, through the end ; .s, 
opening in the liypopharynx for 
tlie salivary duct. — -After Wagner. 
^ 
