TRANSACTIONS OF SECTION D, 441 
space. Continuing along the floor of the mouth, we come to an aperture leading 
downward and backward into the pumping organ; the greater part of this organ 
lies ventrally in the ring, although it extends within the body, to end, somewhat 
abruptly, in the oesophagus. [ 
The pump and adjoining cesophagus are lined with chitin, On cross- 
section the pump is seen to be roughly quadrangular, the top being furrowed 
longitudinally like a V, the bottom showing the same structure reversed. Power- 
ful muscles attached to the ring and the pump serve to expand its lumen; 
another set of muscles causes contraction, and in this respect the mechanism 
of the pump in the tick is more complicated ‘than that of the somewhat similar 
structure which was described in the mosquitoes by Nuttall and Shipley (1903). 
(In this insect the chitinous walls are caused to rebound by their elasticity, with- 
out the aid of contractor muscles.) At the anterior dorsal surface of the pump 
there is a thickened portion’ of chitin, which in cross-section appears triangular 
with the apex pointing downward; and on either side of this, exceedingly minute 
chitinous spicules, arranged like a comb, protrude into the lumen; a somewhat 
analogous structure was described at the posterior end of the pump in mosquitoes 
by the above-mentioned observers. Returning to the buccal cavity, it is seen to 
end posteriorly in a blind pouch, which lies dorsally to the pump. On either side 
of this pouch, between it and the pump, lie the salivary ducts; these run forward 
for a short distance and open into the pouch, close to where the latter joins the pump, 
to form the buccal cavity. They possess a structure (‘spiral thread’) simiar to 
that of trachez, and will be considered later in conjunction with the salivary glands. 
"These ducts, two in number, are very delicate and of considerable size ; as they 
approach the buccal cavity, they pass through a thickened chitinous forarnen whose 
function appears to be to keep them patulous. We have failed to detect any 
pumping structure for the secretion. 
We find that previous authors appear to have misunderstood the buccal 
mechanism; for the few who have attempted to figure it (Heller, Pagenstecher, 
Macleod) have not represented the structure accurately. 
Space and time do not permit us to give a description of other parts of the 
tick. Hitherto the want of material has hindered us in our work on the well- 
known pathogenic ticks of South Africa. Therefore, before concluding our paper, 
we take this opportunity of mentioning to those interested in tick-diseases that 
their co-operation in collecting material for us will greatly aid this research. 
TUESDAY, AUGUST 29. 
The following Papers were read :— 
1. Pearl Oysters and Pearls. By Professcr W. A. Herpmay, /.2.8. 
2. Cephalodiscus.!| By Dr. 8. F. Harmer, B.S. 
3. Demonstration of Ankylostoma Preparations, 
By A. BK, Surprey, LBS, 
1 Published in Reports af the Siboya Expedition. 
