1907.] Wheeler, Fungus-growing Ants of North America. 747 



north in the IVIississippi Valley. ]Mr. Wm. T. Davis has found the typical 

 form as far north as the Raritan River in New Jersey and although he has 

 hitherto failed to take it on Staten Island, it may yet be found in certain parts 

 of Long Island. Both forms of the species have the same habits, although 

 the southern variety often makes larger and more complicated nests and 

 lives in larger colonies than the typical northern form, which is always more 

 or less depauperate, like all ants at the limit of their geographical range. The 

 following description, except in so far as it relates to the size and complexity 

 of the nest, will apply to both forms of the species. 



According to my observations, T. septcnfrlonalis, even in widely separated 

 localities, always occupies a very precise ethological station. I have never 

 found it except in pure sand and in open woods. It is abundant in the post- 

 oak woods of Texas, especially in the neighborhood of Milano and Monto- 

 polis, wherever the red clay is replaced by sand, in the hummocks of Florida 

 (Miami, Jacksonville) and the pine barrens of New Jersey (Lakehurst, 

 Toms River, etc.). The plant associations in all of these localities have a 

 common fades in that they always comprise several species of oaks and 

 many other plants and animals peculiar to the Louisianian portion of the 

 Austroriparian subprovince. 



Externally the nest of T. scpienirionalis is very unlike that of any other 

 North American ant known to me. It consists of a little mound of sand 

 varying from 10 to 20 cm. in diameter, and a few cm. in height, of an ellip- 

 tical, round, or crescentic form and placed at a distance of 5 to 10 cm. from 

 the entrance. The latter is circular and varies from 4 mm. to 1 cm. in 

 diameter, and the gallery into which it leads invariably slopes so as to form 

 an angle with the surface. The sandpile lies in front of the entrance. The 

 external appearance of one of these nests is shown in Fig. 20, from a photo- 

 graph taken at Lakehurst, where the sand is often covered with the needles, 

 twigs and cones of Pinus rigidci and inops. The subterranean portion of 

 the nest consists of from one to three series of straight galleries alternating 

 with more or less spherical chambers, so that it is possible to distinguish a 

 simple and a racemose type. To the former belong the young nests of the 

 var. ohscurior and all the nests of the typical septenirionalis, whereas the 

 racemose type seems to occur only in old and flourishing colonies of the south- 

 ern variety. 



In the table on page 749 are given the dimensions in cm. of the galler- 

 ies and chambers of ten nests of T. septeutrionaU.'^ var. ohxcurior examined 

 in three localities about Austin, Texas, nests A to F being of the simple, 

 and G to J of the racemose type. Diagrammatic sections of nests C, D, F, 

 and G-J, drawn to scale, are represented in Pis. LI to LIII, Figs. 37-42, 45. 

 The entrance gallery is called gallery I, that between chambers I and II, 

 gallerv II and so on. Of the two measurements recorded for each chamber, 



