129 



walled leaf-cells, often with papillae over the lumen. Nearly all' 

 mosses with papillae over the lumen of the cell are xerophytic, or 

 belong in groups that are largely xerophytic. Presumably the 

 papillae tend to retard transpiration. 



Pleurocarpous mosses growing on trees tend to develop short 

 thick-walled cells, especially at the basal angles of the leaves, and 

 a similarity of leaf-structure in the tree-growing mosses due to 

 this fact has produced much of the confusion and uncertainty in 

 classifying such mosses,^, g:, Alsia, Dendroalsia, Bestia, Groiitia, 

 and their relatives. 



Tree-growing mosses also tend to develop erect capsules, and 

 the correlated imperfect peristomes. To some extent this seems 

 to apply to other xerophytic mosses. 



Aquatic or subaquatic pleurocarpous mosses have an apparent 

 tendency to develop enlarged and inflated alar cells. 



Cleistocarpous and gymnostomous mosses appear, for the most 

 part, to be mosses of various relationships adapted to damp soil,, 

 not closely covered with other vegetation, and best suited to 

 support a rather short-lived annual moss. 



The speaker recognized numerous exceptions to the above 

 relationships, if stated as general principles, but, stated as ten- 

 dencies, he believes they are worthy of serious consideration by 

 the systematist, the morphologist, and the ecologist. 



A brief discussion followed. 



The Club adjourned at 5:20 p. m. 



C. Stuart Gager, 



Secretary, 

 May 14, 1907 



The meeting was called to order at the American Museum of 

 Natural History with President Rusby in the chair. One hun- 

 dred and four persons were present. 



The reading and approval of the minutes for April 24 was 

 followed by the presentation of the names of the following per- 

 sons for membership : 



Mr. Theodore Gottschalk, 23 11 Second Ave., N. Y. City; 

 Mr. W. H. Liebelsperger, Fleetwood, N. J. 



The committee appointed at the preceding meeting to arrange 



