416 INFLUENCES OF CULTIVATION 



far from the light of day. In some respects a pit fauna stands 

 on a par with a cave fauna, for many conditions of moisture, 

 light, food and shelter are somewhat similar in both, but 

 while the cave possesses an assemblage of natural immigrants, 

 the coal pit fauna has been introduced by man along with 

 pit-props, with hay and straw for the pit horses, and with 

 other stores. Probably many of the creatures thus forcibly 

 carried underground soon disappear, but several become 

 established and carry on the tradition of their race under 

 new conditions in a new world. Of thirteen species of animals 

 which I recently recorded as inhabitants, at a depth of 750 

 feet, of a coal pit at Niddrie in the Midlothian Coal Field, 

 there is little likelihood that such visitors as a Sparrow, the 

 Beetle Thanasimusformicarius, and perhaps the Two- winged 

 Fly Phora rufipes, were permanent tenants ; on the other 

 hand there is clear evidence that Rats and Mice, Slugs 

 (Limax maximus], Cave Spiders (Lessertia dentichelis), the 

 " Clocker " Beetle (Quedius mesomelinus], Spring-tails 

 (Tomocerus minor], two species of Earthworms, a Myce- 

 tozoon and perhaps the Moth Fly (Psychoda humeralis] 

 had made themselves permanently at home, for the many 

 individuals in the pit included young at various stages of 

 growth or development. 



In this underground world habits were modified less than 

 might have been expected : the Spiders fared sumptuously 

 upon the Insects that frequented the workings, for their webs 

 contained many wings and remains of bodies, the Earthworms 

 were forced to swallow coal dust in place of earth for the 

 organic matter it contained, and the Slugs were driven to a 

 diet of fungus. Solely to the workings of man this little 

 association of animals owed its strange existence in the 

 moistness and perpetual night of a coal pit. 



