ants' nerts. 485 



of the mound-building ants. What purpose does tlie latter serve? 

 Judging from my own observations, the same purpose as the stones, to 

 wit, to procure warmth for the brood. The grass springs ui) in May, 

 and with it the ant mounds. These afford protection against the 

 dampness and the shade of the primeval forest; for such is a meadow 

 to the ants. Up there, under the roof of the inound, the rays of the 

 sun are felt. We have in Europe a small ant {Tapinonia erratictim 

 Latr.) whose perishable earth structures, first described by me, can, 

 to all appearance, serve no other purpose. It builds hastily around 

 the blades of grass a comparatively very high and steep mound of 

 earth, which consists of little more than the upper, superficial, thin 

 vault. Inside there are often only a few wretched thin chambers, 

 especially where the grass is thick. The ants hold their brood partly 

 in their upper jaws, ]>artly lay them on leaves. They crowd together 

 under the mound to warm themselves in the rays of the sun. After 

 the harvest the mounds of the Tapinonia disappear, while those of the 

 other ants remain standing. The latter, however, also become more 

 and more flattened as autumn approaches. Our fig. 12 represents the 

 perpendicular cross section of a nest of Taphionia erraticum Latr., 

 from Vaux, Canton Vaud, Switzerland, which was strengthened and 

 preserved by me by means of a solution of silica, and is now in the 

 Entomological Museum of the Federal Poly teclmikum. Mr. L. Schroter 

 has drawn the nest of two-thirds of the natural size. D, the temporary 

 earthen cupola ; Min, the beginning of the underground mined structure. 



Among us mounds of earth with labyrinths are built by all the spe- 

 cies of Lasius, with the exception of Lasius fuliginosus Ltr,, hrunneiis 

 Ltr., and emarginatus Ol. ; also by Tetramorium cn'S2ntum , the species 

 of Myrmica, several of Formica and Camponotus^ and the species of 

 Tapinoma; and in Tunis by Monomorium salomonis, Apluvno(jaster 

 striola, sardoa, testaceopilosa, crocea, etc. The best artist is the most 

 common of all ants, Lasius niger L., which swarms in all our gardens. 

 This ant also constructs covered passages along the stalks of plants, 

 where in this way it walls up its plant lice and cochineal kermes in 

 artistic stalls. The species of Myrmica frequently build earthen stalls 

 around the jdant lice on the stalks of plants without putting them in 

 communication with the ant-hill by a covered way. 



In the island of St. Thomas I saw earthen structures made by 

 SoIenoj)sis geminata ¥. In Australia the large species of the genus 

 Myrmica, Avliich are 20 to 28 millimeters long, build immense nests of 

 earth. 



A seed-harvesting ant in Colorado, Pogonomyrniex occidentalis Cres- 

 SON, builds a very peculiar and isolated variety of the earthen mounds. 

 It i)lasters or paves the whole upper surface of its earthen mound 

 uniformly and in mosaic with a layer of small white stones, which, 

 according to MacCook's observations, it frequently brings from a great 

 depth in the ground. The still unknown object of this paving is prob- 



