806 Bulletin American Museum of Natural History. [Vol. XXIII, 



Fig. 33. — Nest diagram of Trachymyrmex turrifex (Nest L of the diagram on 

 p. 756), with five well-developed chambers and pendent fungus gardens in all but the 

 first. 



Fig. 34. — Nest diagram of T. turrifex (Nest N of the table on p. 7,56), with four 

 chambers, the lowermost small, recently excavated, and with an incipient garden 

 suspended from rootlets. 



Fig. 35. — Nest diagram of T. turrifex (Nest O of the table on p. 756), with four 

 well-developed chambers and flourishing gardens in three of them. 



Fig. 36. — Nest diagram of T. turrifex (Nest P of the table on p. 756), with five 

 chambers and poorly developed fungus gardens in three of them. This nest shows 

 very clearly the suspension of the substratum from the rootlets hanging into or 

 traversing the chambers. 



Fig. 37. — Nest diagram of Trachymyrmex septentrionalis var. ol>scurior (Nest C 

 of the table on p. 749), consisting of only two chambers, both containing pendent 

 fungus gardens. 



Fig. 38. — Nest diagram of T. oiiscurior (Nest D of the table on p. 749), consisting 

 of three chambers two of which open directly into each other. The mound of 

 sand is .shown in the typical position in front of the oblique entrance gallery. The 

 first chamber contains exhausted substratum ready to be carried out of the nest. 



Plate LIT. 



Fig. 39. — Nest diagram of Trachymyrmex obscurior (Nest I of the table on p. 

 749), of the racemose type, with five chambers. Extending from the single chamber 

 on the right is an unfinished gallery. All the chambers contain well-developed 

 pendent gardens except the first, which is partially filled with exhausted substratmn. 



Fig. 40. — Nest diagram of T. obscurior (Nest J of the table on p. 749) of the 

 racemose type, with seven chambers, six of which are of large size. Of the latter, 

 five contain flourishing gardens but one (to the extreme right) seems to have been 

 only recently excavated by the ants. The crater of this nest was best developed 

 behind the entrance. 



Fig. 41. — Nest diagram of T. obscurior (Nest G of the table on p. 749) of the 

 racemose and horizontally spreading type, with four chambers. The first chamber, 

 in which the mother queen established her colony, had been subsequently enlarged 

 by the workers. 



Fig. 42. — Nest diagram of T. obscurior (Nest H of the table on p. 749) of the 

 racemose type, with four chambers. As in the preceding, the first chamber had 

 been enlarged by the workers, the lowermost was apparently in process of excava- 

 tion. 



Fig. 43. — Cells composing the bromatia of Tyridiomyces formicarum, the pecu- 

 liar fungus grown by Cyphomyrmex rimosus. 



Fig. 44. — Cells composing the bromatia of the same or an allied species of 

 Tyridiomyces grown by Mycocepurus smithi var. borinquenensis. 



Plate LIII. 



Fig. 45. — Nest diagram of Trachymyrmex obscurior (Nest F of the table on p. 

 749), resembling the nests of T. turrifex, with five chambers. 



