50 Zoologica: N. Y. Zoological Society [HI; 3 



the coccids and Azteca foveiceps or more frequently one of the 

 two species of Pseudomyrma or one of the varieties of Ps. 

 maligna. Merely rapping on the tree then reveals the situation, 

 for the angry workers rush out of the petioles, cover the leaflets, 

 trunk and branches and can be readily identified by their size and 

 color, Ps. damnosa being yellow, A. foveiceps and Ps. maligna var. 

 crucians black; maligna s. str. and its var. cholerica both black 

 with yellow markings, but differing in size. Of A. traili only a 

 single very young colony was seen, and this was inhabiting a 

 petiole of a small Tachigalia. There were coccids in the cavity 

 of the petiole, however, and both for this reason and because 

 the ant is known to be associated with other myrmecophytes, I 

 have included it among the obligates in the diagram. It is, in 

 fact, conceivable that in some localities in British Guiana traili 

 may be the dominant species and replace foveiceps in the climax 

 stage of the biocoenose. 



I have noticed unmistakable indications of two other insects 

 on young Tachigalias, both attacking the foliage. One was a 

 caterpillar of some kind, which had gnawed the leaflets of a few 

 plants and had disappeared, so that I was unable to secure a 

 specimen for identification. The other was an Itonidid gall which 

 occurred in great numbers on a single plant on both the upper 

 and lower surfaces of the leaflets. This gall was 2-4 mm. long, 

 erect and cylindrical, with a conical tip, and somewhat resembled 

 the galls produced by Cecidomyia carysecola Osten Sacken on the 

 leaves of our northern hickories. The smaller galls were unde- 

 veloped and contained no larvas but each of the larger ones had 

 a round hole at the tip and contained in the base of its tubular 

 cavity a cylindrical cocoon enclosing the pupa of a small parasitic 

 Hymenopteron, evidently a Eulophid. Some of the specimens 

 were fully pigmented and nearly ready to hatch, others had been 

 killed by an EntomophthoraAike fungus. Pi'obably the mother 

 of the parasite had made the round hole in the tip of the gall 

 in order to enter and oviposit on its maker. 



It will thus be seen that the Tachigalia biocoenose comprises 

 at least 51 different organisms, the host plant and 50 organisms 

 associated primarily with its leaves and terminal shoots or secon- 

 darily with the organisms thus associated. 



