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The species of the Poh-gonaceous genus T ripiar is are also 

 included among the " myrmecophilous " plants, although they 

 are not known to bear extrafloral nectaries or food-bodies, and 

 merely accommodate the ants with dwellings in their hollow 

 stems. Some of the species are said to have bright red flowers, 

 and either for this reason, or because one can hardly touch the 

 trees without being stung by the ants, are widely known in 

 tropical America under the name of "palo santo." 



I was able to study one of the species of Triplaris {T. cum- 

 ingiana Fisch, and Mey.) through the kindness of Mr. Christo- 

 phersen, who guided me to several specimens growing in low, 

 marshy ground at Frijoles on the old line of the Panama Railroad. 

 These trees were 15 to 20 ft. high, with very slender trunk, smooth, 

 light grey bark, and long, narrow, lanceolate leaves. When the 

 trunk was cut down and split longitudinally, it was seen to have 

 a very slender cavity in the centre and extending its full length, 

 and communicating with a similar slender cavit}' in the centre 

 of each branch. This continuous system of cavities communi- 

 cated with the surface by numerous slender galleries, excavated 

 by the ants, and terminating in small round orifices, which served 

 as exits and entrances. Each tree was occupied by a single large 

 colony of Ps. arhoris-sanctce, a yellow species, which is larger and 

 stings more severely than the regular acacia Pseudomyrmas. 

 As the Triplaris trees were isolated, and as their bases must 

 stand in the water during the rainy season, it is difficult to under- 

 stand how the ants manage to exist, unless they remain rather 

 dormant during this season or find some hitherto unknown food- 

 supply on the foliage. 



A second and very different species of Triplaris {T. macombii 

 Don. Smith) was seen in great numbers along the beautiful 

 roadsides of Patulul and Escuintla in Guatemala. This is a 

 larger tree, often attaining a height of 30 to 40 ft., with more 

 diffuse branches and large, coarse, ovate leaves. Early in 

 January it began to put forth bunches of long, yellowish flower- 

 spikes, which were covered with a deciduous sheath. The 

 branches have much larger cavities than in T. cujuiugiana, 

 and the septa at the nodes are not broken through. On examin- 

 ing the surfaces of the branches, each internode is seen to be 

 surrounded near its distal end bv a circle of lenticels, and one of 



