on the Structure of the Mouth in Pediculus. 225 
antennz, and behind this, nearly in the centre of the head, a 
number of small, short muscles radiating in all directions. 
This star of muscles belongs evidently to the little organ which 
was seen in such violent pulsation whilst the animal was suck- 
ing; and we have without doubt here met with a “pumping- 
ventricle’’—that is, one of that kind of organizations of the 
swallow which have long ago been discovered in Aranee and 
Tardigradi, and which, no doubt, are of frequent occurrence in 
Arthropoda living by suction. I have discovered them myself 
in those coleopterous larvee which have powerful organs for biting, 
placed at a distance round a very minute mouth-opening, such as 
the larvee of Carabi, Hydrophili, and Histri—as well as in the 
larvee of Dytisci, which suck through the mandibles. Nor can 
we escape the supposition that an organ of which the function 
mechanically so much resembles that of a heart, must also in 
essential points be so far constructed like a heart, and conse- 
quently possess valves calculated to force the current of blood 
the right way. But we shall hardly succeed in clearing up this 
point with sufficient certainty with our present means of inquiry, 
because the diminutive size of the ventricle and its recondite po- 
sition, deeply imbedded in a mass of muscles in the centre of the 
head, render a dissection a matter of very doubtful success, whilst 
the immense rapidity of the pulsation renders the observation 
during the suction unreliable—the thickness of the overlying 
parts at the same time preventing the use of very strong mag- 
nifying-powers. And thus we are compelled still to acknowledge 
the truth of the venerable Leeuwenhoek’s words: “ Preeterea 
pro certo habentes adhuc millenas in capite pediculi esse res, que 
oculos nostros semper latebunt.” (Arcana Nature, Hpist. 77. p. 
388, Jan. 1694.) 
In the centre of the large conical bundle of muscles there is a set 
of slender chitinous organs, which at their roots are all bent to the 
sides, evidently in order to offer favourable points of insertion to 
the muscles by which it is to be protruded ; for it is evident that 
these organs must be pushed forwards out of the head, at the con- 
traction of those muscles which are fixed between their outwardly 
bent extremities and the part of the skull which is in front of 
them. And thus we can understand why the protruded organs 
of the mouth disappeared the moment a pressure from without 
was exercised on the head ; for it is evident that the greater the 
pressure the more was that force paralyzed which kept these organs 
in their protruded position. But at the same time it will be un- 
derstood that, whilst this arrangement renders it impossible to 
press the organs of the mouth out through the opening of the 
mouth, it renders it at the same time easy to pull them from be- 
hind out of the muscular bundle in which they are imbedded. 
Ann. & Mag. N. Hist. Ser.3. Vol. xvii. 15 
