476 Mr. Blackwali. on the 



lanogaster, and Salticus scenicus, for example, have only two clazvs 

 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, 

 which have a considerable degree of curvature, are finelypointed^ 

 and are furnished with tooth-like processes on the under side 

 (Tab. 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 efficient 



instruments 



