No. 415.] NESTS OF AMERICAN ANTS. . 527 
Cryptocerus aztecus Forel. 
Cryptocerus wheeleri Forel. 
Leptothorax petiolatus Forel. 
. Pseudomyrma gracilis Fabr., var. mexicana Em. 
Sans 
Of these species, which are here enumerated in the order of 
decreasing frequency, —the first being far and away the most 
abundant, — I noticed the following combinations occurring in 
single buds: Nos. 1+2; Nos. 1+2+4; Nos. 1-34 4j 
Nos. 13- 5 +6; Nos. 1 +7. 
While I am not certain that the nests of the different species 
could communicate with one another, I am confident, neverthe- 
less, that these ants must be very tolerant of one another, for 
their entrances were situated on such a small surface as to be 
of necessity very close together. This is the more astonishing 
on account of the great diversity of behavior exhibited by the 
different species. When I was tearing the leaves asunder the 
little Cremastogasters attacked me vigorously, but their lillipu- 
tian stings and mandibles could scarcely perforate my epidermis. 
The huge Camponotus abdominalis, however, rushed out in a 
body, and the powerful mandibles of the soldiers, reinforced by 
the copious formic acid batteries of the whole company, often 
compelled me to drop the tillandsia and forego further explora- 
tion of its leaves., The two species belonging to the grotesque 
genus Cryptocerus were as gentle as lambs, preferring to rest 
quietly on my hands and clothing. The timid little Leptothorax 
took to their legs, while the superb wasp-like Pseudomyrmas 
made dashes at me from among their glistening larvae and 
Pupz, but returned with precipitation as if afraid to abandon 
their offspring. 
As the tillandsias appeared to suffer no injury from their 
tenants, and were even preparing to send forth their long spikes 
of reddish flowers, I was at first inclined to see in this associa- 
tion of plants and ants another case of symbiosis (sensu stricto). 
But apart from v. Ihering's contention (94 p. 365 e seg.) that 
the number of « Ameisenpflanzen" in tropical America has 
already been considerably exaggerated, the above view also 
loses in probability from the fact that at least four of the seven 
