304 ARACH NIDA—-SCORPIONIDEA CHAP. 
are coxa, trochanter, femur, patella, tibia, protarsus, and tarsus, and 
it is certainly convenient that each joint should have a separate 
name, but it must be borne in mind that the tibia of different 
authors is not always the 
same joint. Special atten- 
tion must be directed to 
the three terminal joints, 
which furnish highly 
important characteristics. 
The tibia (Cn _ Pocock’s 
sense) is sometimes pro- 
vided with a“ tibial spur ” 
at its lower distal ex- 
tremity. From the soft 
arthrodial membrane be- 
tween the protarsus and 
tarsus may proceed one 
; or dark-tipped claw- 
ccxa; 2, trochanter; 3, femur; 4, patella; more dark-t PRES py 
5, tibia; 6, protarsus; 7, tarsus; p.s, pedal like spurs, the . “ pedal 
, p ; } i 
spur; ¢.s, tibial spur. B, Fourth tarsus of , wee : wes 
Palamnaeus swammerdami ; 1, lateral lobe. epee: The terminal 
(After Pocock. ) joint (tarsus of Pocock) 
is variously furnished 
with hairs and teeth, and always ends in a pair of well- 
developed movable claws beneath which a much reduced and 
sometimes almost obsolete third claw is distinguishable. The 
tarsus generally projects in a “claw-lobe” over the base of the 
superior claws, and sometimes lateral lobes are present. The 
first and second coxae have triangular maxillary lobes directed 
towards the mouth. The third and fourth coxae are fused 
together on each side, and those on one side are separated 
from those on the other by the sternum. In other respects 
the four pairs of legs are usually similar. 
Fic. 170.—A, Diagram of a Scorpion’s leg; 1, 
Internal Anatomy. 
The alimentary canal is a fairly uniform tube, nowhere 
greatly dilated. The very small mouth leads into a small 
suctorial chamber, and this is connected by a narrow oesophagus, 
which pierces the cerebral nerve-mass, with a slightly dilated 
portion which receives the ducts of the first pair of gastric 
