in May of last year, but produced no ovaries in any of 
the flowers examined. There are native specimens of it 
in the Kew Herbarium from Mexico, Central America, 
Panama, and St. Martha, in New Grenada. 
Far more interesting than the synonymy of these horned 
Acacias is the fact that when found they play a wonderful 
part in the economy of nature, by housing and feeding @ — 
tribe or tribes of ants which find their habitation in the | 
stipular thorns, and their food in the fleshy appendages 00 — 
the tips of the leaves; a hospitality which they repay. with — 
interest, by waging a successful war against the armies of 
leaf-cutting ants who would otherwise soon extirpate the — 
Acacias. 
This curious subject was carefully studied by the late 
observant Naturalist, Mr. Th. Belt, whose published | 
account of it is so interesting, that, feeling sure it will be 
welcome to the readers of the “ Botanical Magazine,” Is 
herewith extract it.—J. D. H. 
‘These thorns are hollow, and are tenanted by ants — 
that make a small hole for their entrance and exit near 
one end of the thorn, and also burrow through the partl- 
tion that separates the two horns, so that one entrance 
serves for both. Here they rear their young, and in the 
wet season everyone of the thorns is tenanted; and 
hundreds of ants are to be seen running about, especially : 
over the young leaves. If one of these be touched, OF 
a branch shaken, the little ants (Pseudomyrma bicolor, — 
Guer.) swarm out from the hollow thorns, and attack the 
aggressor with jaws and sting. They sting severely, 
raising a little white lump that does not disappear in less_ 
than twenty-four hours. 
** These ants form a most efficient standing army for 
the plant, which prevents not only the mammalia from 
browsing on the leaves, but delivers it from the attacks 0 
: me more dangerous enemy—the leaf-cutting ants. 
so services the ants are not only securely houses 
; = : sas i but are provided with a bountiful supply 1 | 
Sosa 0 secure their attendance at the right time a2 
place, this food is so arranged and distributed as to effect 
that object with wonderful perfection. The leaves are Dr 
pinnate. At the base of each pair of leaflets, on the mid- 
rib is a crater-formed gland, which, when the leaves ar¢ 
