6 Adams, 0?i tlie Mole {Talpa eiiropced). 



honoured figure originating from Geoffroy Saint-Hilaire, 

 elaborated by Blasius, and copied from him by every 

 succeeding writer, apparently without the sh"ghtest attempt 

 at verification. The oldest figure of all, viz., that in Cadet 

 de Vaux's work, is evidently drawn from an actual dissec- 

 tion, and not from memory aided by imagination, as is 

 evidently that of Saint-Hilaire. 



The text-books all speak of the fortress as if it were 

 made on a pre-arranged plan of labyrinthine escapes from 

 enemies above and below, whereas my observations tend 

 to show that the more or less complicated galleries are 

 purely incidental and without any reference whatever to 

 premeditated escape, except in the case of the bolt-run, 

 which will be described presently. 



That there should be a general resemblance in struc- 

 ture is of course natural, and is the case, and the dissection 

 of only one or two fortresses might well give the observer 

 the idea that the galleries were splendid examples of a 

 wonderful instinct of preservation. 



But, by watching the erection of these structures from 

 day to day, the conclusion forces itself upon one that 

 these galleries are the natural, incidental, and inevitable 

 outcome of the zvork of excavating the nest-cavity and piling 

 up the superincumbent mound. 



The site for the fortress having been determined, a 

 circular cavity as a receptacle for the nest is made from 

 two to six inches below the original surface of the 

 ground, except in boggy soil or low-lying land liable 

 to floods, where the nest is often above the ground level 

 in the centre of a heap of earth which is thrown up from 

 converging runs {Figs. 5, 6, 7). Now, the easiest way 

 to dispose of the earth when the nest-cavity is being 

 excavated is to push it upwards on to the surface, and in 

 order to do this a tunnel must be made. Fi^. 8 shows 



