296 OBSERVATIONS ON INSECTS. 



It often remains at rest in the same spot for several 

 seconds together, with its antennae extended and 

 motionless, but its feet in a state of intense vibra- 

 tion, and then after a while suddenly darts off to 

 another situation with wonderful rapidity. It would 

 seem also to be tenacious of life ; as I observed that, 

 amid a large variety of different Entomostraca that 

 were kept in a vessel of water, which was not 

 changed for a considerable time, it survived all the 

 others by several days. 



Argulus foliaceus.* In 1835, 1 found this singular 

 species, which has been very little noticed by English 

 naturalists, in fish-ponds at Ely in great abundance. 

 They are there parasitical on pike, adhering to dif- 

 ferent parts of the body of that fish. The fishermen 

 called it the pike-louse. 



ELECTRIC CENTIPEDE, f 



Dec. Wth, 1843. A MAN brought me to-day what 

 he called two glow-worms, which he had seen shining 

 on a bank the preceding evening. They proved to 

 be only the electric centipede, which is frequent in 

 the autumnal months in this neighbourhood, and 

 may often be seen shining by road-sides, more espe- 

 cially on mild damp evenings. They are constantly 

 mistaken for glow-worms by the common people. 



* Hist. Nat. des Crustaces, torn. iii. p. 444. 



t The Scolopendra electrica of authors ; but probably under 

 that name two or more species have been confounded, as I suspect 

 there are at least two in this country which are luminous. It 

 belongs to the genus Geophilus of Leach. 



