﻿Tracks of Insects Resembling the Impressions of Plants. 51 



regular series of impressions, corresponding to the toothed rim ; 

 while they also bear a resemblance to the marks made by the ani- 

 mal when forcing a passage through the soft clay, and so produc- 

 ing the rising on the bottom of the blunt points seen on the exterior. 

 But as we find on the bottom the same tracks that are on the ceil- 

 ing of the gallery, it is evident that the animal has turned on itself. 



The appearance of the ridges on the ceiling of the gallery, as 

 well as their size, remind one at once of the galleries of the mole- 

 cricket. It should not, however, be inferred from this, that I believe 

 these animals to live in the water. This has been brought to my 

 mind very lately, by a letter from our member, M. Schlumberger, 

 who, knowing the locality, remarks, that the ponds of the shelves 

 of Villers are dry, at least, in part, during nearly all the summer, 

 and that it would be urged against my facts, that the mole-crickets 

 must have lived in places around these ponds, and extended their 

 wanderings in search of food. I have, therefore, examined, as well 

 as I could, the nature of the tracks of such animals as ought to live 

 near these galleries. It is not possible to place under the necessary 

 conditions, the living specimens of mole-crickets I have secured. 

 I have, therefore, only experimented with the dead individuals, to 

 see the tracks made by the jagged, comblike hind feet, as they 

 press the earth. I have thus produced the toothlike impressions 

 of the ceiling, left on the edge of the clay, and formed by these 

 same feet, alternately to the right and to the left, just as they were 

 made by the insects whence forcing a passage. I have given these 

 details in full, and will add as a confirmation of them, that I have 

 observed, in two or three parts of the ceilings of the galleries, the 

 linear imprints, very delicate, fine, transverse striae, identical with 

 those produced by the antennae of the same insects when resting 

 lightly on the soft clay. It is thus positively to these mole-crickets 

 (Gryllotalpa vulgaris), that we can attribute the tracks that I have 

 observed. 



I have, till the close, reserved my remarks on the analogy that 

 these tracks present to the impressions of plants. If the ponds of 

 Villers were to be covered by a deposit of sand, there can be no 

 doubt that the more the sand penetrated into the galleries, the 

 deeper the imprint of the mold would be made in the layer of grit ; 



