34 MYRIAPODA 



of the Julidae or Polydesmidae, or may be of a dull and rusty 

 iron colour, or quite black. 



One of the strangest peculiarities found among Myriapods is 

 that some of them (e.g. Geophilus electricv.s) are phosphorescent. 

 As I was walking one summer evening near my home in 

 Cambridgeshire I saw what I thought was a match burning. 

 Looking more closely, I saw it move, and thinking it was a 

 glow-worm I picked it up, and was surprised to find that it was 

 a Geophilus shining with a brilliant phosphorescent light. I let 

 it crawl over my hand, and it left a. bright trail of light behind 

 it, which lasted some time. I have been told that this species 

 is common in Epping Forest ; also in Cambridgeshire. 1 



Besides G. electricus, G. pliosphoreus has been described as 

 a luminous species by Linnaeus, on the authority of a Swedish 

 sea captain, who asserted that it dropped from the air, shining 

 like a glow-worm, upon his ship when he was sailing in the 

 Indian Ocean a hundred miles from land. 



What the use of this phosphorescence may be is not known with 

 any degree of certainty. It may be either a defence against 

 enemies, or else a means of attracting the two sexes to one another. 



The places which the Myriapods select for their habitation 

 vary as much as their colour and size, though, with a few excep- 

 tions, they chose dark and obscure places. A curious species of 

 Myriapod is Pseudotremia cavernarum (Cope), which is found in 

 certain caves in America. The peculiar life it leads in these 

 caves seems to have a great influence on its colour, and also 

 affects the development of its eyes. Mr. Packard's account 

 of them is worth quoting : " Four specimens which I collected 

 in Little Wyandotte cave were exactly the same size as 

 those from Great Wyandotte cave. They were white tinged, 

 dusky on the , head and fore part of the body. The eyes are 

 black and the eye-patch of the same size and shape, while the 

 antennae are the same. 



" Six specimens from Bradford cave, Ind. (which is a small 

 grotto formed by a vertical fissure in the rock, and only 300 to 

 400 yards deep), showed more variation than those from the two 

 Wyandotte caves. They are of the same size and form, but 

 slightly longer and a little slenderer. . . . The antennae are 

 much whiter than in those from the Wyandotte caves, and the 



1 See L. Jenyns' Observations in Nat. Hist. London, 1846, p. 296. 



