390 



ANNUAL REPORT SMITHSONIAN INSTITUTION, L921. 



Fig. 5. — Acacia ant, 

 Pseudomyrma belti, 

 var. f ulvescen s, 

 worker; showing 

 elbowed antennae 

 and sting. From 

 Tanquian, state of 

 San Luis Potosi, 

 Mexico. X 6. 



i lie legumes of ;i bean, showing the seeds in two rows, embedded 

 in sweetish pulp; this group I have called the "Bean pods" or 

 Leguminiferae. The third group (c) has curved pods, with the seeds 

 in a single row, embedded in a feltlike pulp; this group I have 



called the " Simitar pods," or Acinaceae. The last 

 group (d), distinguished by its long two-valved 

 legumes, I have called the Globuli ferae, on account 

 of the globose shape of the flower heads (pis. 12 

 and 13). 



ACACIA ANTS OP MEXICO. 



In 1908, through the kindness of Don Luis G. 

 Cuevas, of San Luis Potosi, to whom American 

 scientists are indebted for many favors, I received 

 several colonies of living ants in the thorns of 

 bull-horn acacias collected at Tanquian in the dis- 

 trict of Tancanhuitz, State of San Luis Potosi. 

 When the box was unpacked in my office, the 

 furious little insects came swarming out, some of 

 them climbing up my legs and stinging me severely. 

 All of these ants came from the thorns of Acacia 

 sphaerocephala, easily distinguished from A. hernandezii of the same 

 region by their pale j^ellow color and their less widely spreading and 

 straighter form. The ants of a tawny yellow or reddish color with 

 darker abdomens, proved to be Pseudomyrma belti var. fulvescens, 

 closely allied to the typical darker 

 colored Pseudomyrma belti. Spec- 

 imens of them deposited in the 

 collection of the Bureau of En- 

 tomology were forwarded by 

 Mr. S. A. Rohwer to Professor 

 Wheeler, who kindly identified 

 them. Beautiful photographs of 

 workers and a male ant were 

 made for me by Mr. H. S. Barber, 

 of the Bureau of Entomology (pi. 

 14). Drawings are also shown in 

 figures 5 and 6 to illustrate the 

 structure of these interesting in- 

 sects. As shown in these figures 

 both the male and the workers 

 have the abdomen or gaster connected to the thorax by means of two 

 slender segments technically known as the petiole and post-petiole. The 

 longer and more slender male is distinguished by a pair of cerci at the 



■Si>s 



Fig. 6.— Acacia ant, Pseudomyrma belti, 

 var. fulvescens, male; showing long 

 curved antennae and pair of cerci at the 

 end of the abdomen. X 6. 



