- 416 Mr. BLackwAtut on the 
lanogaster, and Salticus scenicus, for example, have only two claws 
on each foot; and if the tarsi of the larger Geometric Spiders 
indigenous to Great Britain, such as Epeira cicatricosa, Epeira 
Diadema, and Epeira apoclisa, be examined under the microscope 
with a high magnifying power, it will be distinctly perceived 
that the inferior part of their feet is provided with several claws, 
whichhave a considerable degree of curvature, are finely pointed, 
and are furnished with tooth-like processes on the under side 
(Tas. XXXI. Fig. 4.); and should the investigation be extended 
to other retiary spiders, the feet of many species which con- 
struct complicated snares will likewise be found to exhibit a 
similar organization. As the best means of guarding against 
errors, to which the inspection of limbs defective in structure 
might conduce, it is advisable to select the legs of vigorous 
individuals which have recently moulted, whenever such can be 
procured. 
The supernumerary claws were first observed by me in exa- 
mining the feet of Epeira apoclisa ; and in every instance I 
counted as many as five, which, with the three upper ones 
previously known, give a total of eight claws on the same foot, 
distinguishable at a glance from the coarse setaceous bristles in 
their vicinity. "There is also a strong moveable spine inserted 
near the termination of the tarsus of each posterior leg on the 
under side, which curves upwards at its extremity, and exhibits 
a slight irregularity of outline at its superior surface. The 
function performed by these spines is an important one. By 
the contraction of their flexor muscles they are drawn towards 
the foot, and are thus brought in immediate opposition to the 
claws, by which means the animal is enabled to hold with a 
firm grasp such lines as it designs to attach itself to. Now, as 
the spines and the spinning apparatus are the most eflicient 
instruments 
