238 BOTAXICAL GAZETTE [septemb 



on various parts of small silphids, especially, and on the wings of 

 certain flies in the tropics. They may produce conspicuous and 

 dense tufts, and in some instances correspond very closely in 

 external form to types of Cladophora. No characteristic foot is 

 developed and no definite spores have been seen, propagation 

 being effected, as far as can be determined, solely by fragmentation. 



Hormiscium myrmecophilum, nov. sp. — Plate XIX, figs. 22-25 



Filaments nearly hyaline becoming brownish, darker near the 

 base, closely septate, the cells often as broad as, or broader than 

 long, undifferentiated, distally bluntly rounded, erect or curved 

 upward, rigid, simple, less frequently sparingly branched, tapering 

 but slightly if at all, one to several arising from a deeply blackened 

 foot of variable size and shape. Maximum length about 280 ju 

 by 7-8 n in width. 



On various parts of Pseudomyrmex sp., Amazon (Mann). 



This plant was received from Mr. W. H. Mann, who found it 

 growing on a majority of the individuals taken from a nest of 

 Pseudomyrmex, while he was acting as entomologist of the Leland 

 Stanford Expedition to Brazil in 191 1. It is sufficiently large to 

 be readily visible as it projects from the surface of the host, and, 

 although it is such an insignificant type, possesses sufficient indi- 

 viduality to distinguish it. It produces no definite spores or differ- 

 entiated cell-groups, as far as has been observed, and appears to 

 propagate itself by fragmentation only, the filaments proliferating, 

 as indicated in the figures, after a terminal portion has been broken 

 off. The opaque and somewhat variable "foot," by which the 

 individuals are attached to the surface of the host, appears to cor- 

 respond to such a small fragment broken from a hypha, which, 

 adhering laterally, becomes blackened and indurated, and gives 

 rise to new filaments, while at the same time it serves the office of 

 attachment as well as of food absorption. It is not, however, so 

 firmly fixed as is the case with most of the Laboulbeniales, and 

 might be easily removed by its host from portions of the body which 

 can be reached by the mouth. When one considers the habits 

 of cleanliness which characterize most ants, it seems singular that 



