756 



Bulletin American Museum of Natural History. [Yo\. XXIII, 



sionally I have found nests Avith abnormal turrets, like the one represented 

 in PI. L, Fig. 27, which has the summit enlarged and spreading and pro- 

 vided with three distinct orifices. The pellets of earth brought up by the 

 ants are cuboidal or polyhedral, of uniform size and measure about 2 mm. 

 in diameter. They are not cast to one side as in septentrionalis but in a 

 closed circle at a distance of 8-12 cm. from the entrance. Ks this circle 

 grows in height it forms a very shallow crater Avith the turret rising abruptly 

 in its center. In the post-oak Avoods and cedar-brakes the castings are red 

 or dull vermilion and contrast strongly Avith the black soil or dead leaA^es 

 of the surface. 



The galleries and chambers alternate Avith one another as in the simple 

 type of septentrionalis nests, but the chambers are smaller and the galleries 

 are much longer and usually descend Aertically into the soil. These differ- 

 ences are distinctly shoAvn in the figures (PI. LI, Figs. 33-36) and in the 

 measurements (in cm.) of the accompanying table. 



Atta (Trachymyrmex) turrifex Wheeler. 



All of these nests Avere located in the clayey soil of the post-oak Avoods 

 except the last (R) Avhich Avas in pure sand. OAving to the length of its 

 galleries, this is exceptional in its total depth (110.5 cm.), and therefore 

 abnormally increases the aA-erage length of the galleries I to V in the table. 

 The aA'erage depth of nests K to Q is only 50.8 cm. Avhich is less than half 

 the depth of nest R. The nests usually comprise four chambers (Fig. 25), 

 but fiA-e are often met Avith, and here, as in septentrionalis, the galleries and 

 chambers haA^e their dimensions suddenly increased, beloAv the first chamber, 

 which is the Avork of the mother ci(ueen. I have seen but one turrifex nest 

 that resembled the racemose type of septentrionalis in having tAA'o branches 

 to Gal. IV, each terminating in a chamber. Comparing the nests of the tAA'o 

 species aa'c see that both start Avith the simple, primitive type consisting of 



