THE FAUNA OF A COAL-PIT AT GREAT DEPTHS 183 



our young collector was requested to be on the look out for 

 "mushrooms" in the neighbourhood of the Slugs, and the result 

 was the collection of quantities of Polyporus destructor (see 

 Introduction) and the small slime-fungus, Stremonitis fusca. I 

 have no doubt that the former of these formed the main food- 

 material of the Slugs. 



ARACHNIDA. 

 SPIDERS. 



5. Lessertia dentichelis (Simon). 



Tineticus dentichelis (Simon). Arach. France, vol. v. 18S4, p. 390, 



figs. 167-169. 

 Tineticus simplex. F. O. Pickard-Cambridge, Ann. Mag. Nat. 



Hist., ser. vi., vol. x. 1892, p. 384, pi. 20, fig. 5 a-g. 

 Macrargus dentichelis (Simon). Berland, Arch. Zool. exp. et gen., 



191 1, ser. v., vol. vi., Notes et Revue, p. cxiv., figs. 6, 7. 

 Lessertia dentichelis (Simon). Simon, Arch. Zool. exp. et gen., 191 1, 



ser. v., vol. ix., p. 185. 



A considerable number of these little Spiders were captured 

 moving actively on the rock roof of the workings, on the wooden 

 props, on brick barriers, and on the coal itself. Clearly it was quite 

 at home in the darkness and at the great depth, for its delicate 

 sheets of net were common in the workings and were evidently of 

 good use for they contained many insect wings. Several small 

 cylindrical white cocoons found near the webs probably contained 

 young of this form. Viewed in relation to its coal-pit existence, the 

 previous records of the habitat of Lessertia dentichelis are of some 

 interest. There appear to be two more or less distinct modifica- 

 tions ; one variety {sub-lucicole) prefers an existence under conditions 

 of subdued daylight, and has been found so far only in France, 

 in Var and the Alpes-Maritimes (Simon, 1884), and in one of the 

 courts of the Sorbonne in Paris (Berland, 191 1). The other form 

 {lucifuge) frequents only places from which light is absent. It has 

 been found once in England, on the " damp walls of a brewery cellar 

 at Cannock, Staffordshire" (Pickard-Cambridge, 1892); in the cata- 

 combs of Paris (Berland, 191 1), and in various grottoes, "baoumo," 

 and subterranean river -courses in the French departments of 

 Ardeche, Gard, and Ariege (Simon, 191 1). It has been stated 

 (Berland, p. cxiv.) that differences of smaller size, less colour, eyes 

 slightly more closely set, anterior tooth of chelicerre shorter and as 



