48 CENTIPEDES 



The first reaches a peak of abundance in wet forest communities, 

 the second in dry forest, while A^. voracior is plentiful in those 

 localities in which floor moisture conditions are intermediate: and 

 this distribution is related to the different times of survival of 

 the three species when placed in dry air. It is of course true that 

 certain centipedes such as Scutigera, Scolopendra and Dignathodon 

 spp., and in our own country Lithobiiis calcaratus, tend to inhabit 

 dry places, but it is probable that this phenomenon is analagous to 

 that found in woodlice and that the different species vary merely in 

 the length of time that they can survive away from dampness. 

 Recently Palmen and Rantala (1954) have suggested that the orien- 

 tation of the Geophilid centipede Pachymerium ferrugtneum in its 

 natural habitats, is chiefly guided by reactions to air humidity and 

 moisture and, to a lesser degree, to temperature. When the relative 

 humidity of the air decreases in a niche inhabited by this species, 

 the result will be an increase in locomotory activity and orienta- 

 tion towards moisture. If high temperature is combined with un- 

 usually low atmospheric humidity, the increased desiccation 

 caused will intensify the responses of the animal to moisture. 



Many species of centipedes are cave-dwellers and a few of the 

 Geophilomorpha are marine. Two British species are found on 

 the seashore under stones and seaweed at low tide level. The 

 smaller, Scolioplanes maritimus, was first discovered by Leach in 

 1817, who wrote somewhat optimistically, 'Habitat in Britannia 

 inter scopulos ad littora maris vulgissime'. It was re-discovered 

 some fifty years later at Plymouth and has since turned up in the 

 Isle of Man, Somerset, Cornwall, Sussex, Co. Dublin and on the 

 coast of Galway. It is evidently fairly widely distributed on the 

 North Sea coast of France, Denmark, Sweden and Germany. The 

 second species, Hydroschendyla submartna, is very much less com- 

 mon. It has nevertheless been found in Cornwall, Jersey and 

 Yorkshire, as well as on the coasts of France, Italy, Scandinavia, 

 North Africa and Bermuda, where it lives in muddy situations 

 around the edges of eroded flat stones, and in isolated honey- 

 combed blocks of limestone about nine inches below mean high 

 water (Chamberlin, 1920). Pectinunguis americanus occurs under 

 seaweed, driftwood etc. on the coasts of Mexico, including Florida 

 and the coasts of lower California, and other marine centipedes 



