BATHYPOREIA. 187 



very nimbly, and is difficult to catch, making for the 

 bottom immediately on being disturbed. Besides the Pro- 

 teus anguinus, these caves have several peculiar insects and 

 Ajptera. Dr. Schioedte has described, in the work cited, as a 

 new species the Niphargus, which Mr. Westwood exhibited 

 at the Linnean Society (Proc. Linn. Soc. April, 1853) as 

 N. slygius. 



Niphargus aquilex, Schioedte. The Well Screw. — 

 Snow-white ; the epimera are all shorter than their corre- 

 sponding segments in depth ; eighth, ninth, and tenth seg- 

 ments nearly equal in depth. From three to four lines in 

 length. 



Found in great numbers in a well near Maidenhead, the 

 water of which was, in consequence, rendered unfit for use. 

 May not this be the Gammarus suhterraneus alluded to by 

 Leach in the seventh volume of the ' Edinburgh Ency- 

 clopaedia '? 



Gen. 87. BATHYPOREIA, Lindstr* 

 Upper antennae with second joint of the peduncle pro- 



* Mr. Spence Bate now refers his genus Thersites to this, and the species 

 T. Guilliamsoniana to Bathyporeia pilosa. 



