STRIDULATION IN SOME AFRICAN SPIDERS. 17 
adjacent hairs of the oral fringe, being longer and more bristle- 
like, as, for example, in H. tigrina. These two rows of bristles 
are evidently designed to catch against and shake the tips of the 
long feathery bristles which rise up amongst the hairs clothing 
the area upon the maxilla between the suture (Fig. 1, B, d) and 
the oral fringe (B, e). 
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Fie. 1.—Stridulating organ of Harpactura chrysogaster. 
A. Outer surface of mandible, showing a, fang; b, pad of feathery hairs ; 
c, oral fringe and two rows of modified bristles between the pad and the 
fringe. 
B. Inner surface of maxilla, showing the cluster of plumose bristles 
between the suture d and the oral fringe e. | 
Structurally, this organ, characteristic of Harpactira, calls to 
mind the organ possessed by the Oriental genera Citharognathus, 
Phormingochilus, &c. In these, too, the outer surface of the 
mandible is furnished with a pad of feathery hairs, and the notes 
or vibrating bristles are also plumose; they are not, however, 
situated on the maxilla, as in Harpactira, but upon the mandible, 
and result merely from the enlargement of a few of the hairs of 
the feathery pad. 
The next organ to be described, though resembling the others 
in principle, differs entirely in position. Instead of being lodged 
4ool. 4th ser. vol. II., January, 1898. c 
