1906.] Wheeler, The Ants of the Grand Canon 3 55 



miles through a chasm of this character ; but the evidence at hand in- 

 dicates that it does. . . . The inference is that the Hfe of the Painted 

 Desert is derived from the deserts of western Arizona, and that it 

 came by the roundabout way of the Grand Canon of the Colorado." 

 Merriam also calls attention to the occurrence near the bottom 

 of the canon of two lizards (Sceloporus clarkii and Uta symmet- 

 rica) "which belong to the torrid fauna of southern and western 

 Arizona, and are not known to reach the Painted Desert." I believe 

 that Merriam's interpretation will also hold good of the origin of the 

 ant-fauna in the lower zones of the canon; this fauna has simply 

 advanced up the long, deep chasm from the deserts around the lower- 

 most portion of the river. Further collections of the ants at different 

 points in the canon will undoubtedly add several desert species to 

 my list. Among those which should occur at the lower elevations 

 in the caiion are certain pale varieties of the honey ant {Myrmeco- 

 cystus melliger) and of Dorymyrmex pyramicus (var. hicolor) which 

 are common in the Mojave Desert, several species of Pogonomyrmex 

 (P. descrtorum, dentatus and varieties of P. californiciis and imber- 

 bicidus), and above all the desert species of Pheidole and Stenamma 

 (S. [Ischnomyrmex] cockcrelli and alhisetosum and 5. [Messor] per- 

 gandei). One of the most interesting ants of the deserts of Arizona 

 and California is Messor pergandei, which builds flat craters from a 

 foot to 18 inches in diameter, with single or double entrances of very 

 irregular outline, and garners great quantities of seeds. Isch- 

 nomyrmex c acker elli and alhisetosum make similar but larger nests 

 and have very similar habits. Owing to the limited supply of 

 insect food obtainable in the desert during the greater part 

 of the year, these ants, like the species of Messor, Pogonomyr- 

 mex and several species of Pheidole, are compelled to subsist on 

 seeds. 



Further details concerning the ants found in the Grand Canon, 

 together with descriptions of a few new forms, are included in the 

 following systematic list: 



Subfamily Ponerin^. 



1. Ponera opaciceps Mayr. — Several workers of this species were 

 collected under stones beneath the willows of the Indian Garden. 

 A single individual was taken in the bottom of a creek near the river. 



Subfamily Myrmicin^. 



2. Myrmecina graminicola SLTaericana."" Emery var. brevispinosa 



Emery. — Several workers which agree very closely with northern 



