THE CANADIAN ENTOMOLOGIST. 355 



f 



The parallelism of structure, the apparent identity of ecological 

 relationship and the suggestion of some peculiarities of geographical dis- 

 tribution seemed to justify the extensive investigations necessary for the 

 elaboration of the problem. 



The final treatment of the various phases of the problem is not yet 

 ready for publication, but quite a full discussion appears in the Sixteenth 

 Annual Report of the Missouri Botanical Garden. It is the purpose of 

 the present note to direct the attention of entomologists to a phase of 

 ecology and biogeography, which is of interest to both botanists and 

 zoologists, and requires the co-operation of both groups of workers. 



The plant forms to be considered were limited to those in which the 

 anthers open by terminal pores instead of the more general longitudinal 

 slits. Detailed structural comparisons have shown that flowers with apical- 

 ly dehiscent anthers may be divided upon structural grounds into seven 

 groups. Like most categories of classification, these groups are not 

 sharply defined, but in some degree transgressive. The distinction 

 between dehiscence by pores and by longitudinal splits and between the 

 several types recognized is not an absolute one. The number of apically 

 dehiscent genera or species might be increased or decreased by including 

 forms in which the lateral slits first open more widely at the tip, or ex- 

 cluding all those in which the pores are finally supplemented by lateral 

 slits. The number of genera as limited is, the writer feels confident, 

 approximately right so far as may be determined from systematic literature 

 and the examination of herbarium material. The groups, too, cannot be 

 separated by sharp characters, but the questionable forms are but few as 

 compared with those which do fall clearly into one of the recognized 

 classes. 



The classes recognized have been designated as the Araceous, 

 Gramineous, Polygalaceous, Ericaceous, Dilleniaceous, Solanum-Cassia 

 and Melastomataceous types. The first three of these represent well- 

 defined groups, which are quite foreign to our present consideration. 

 The Ericaceous type is not so sharply limited, and perhaps includes 

 some forms which should have been placed in one of the other types. 

 The Dilleniaceous, Solanum-Cassia and Melastomataceous types are the 

 ones to which especial attention has been given. 



The Dilleniaceous type has both whorls of the perianth usually 

 developed, but one or both sometimes reduced, usually campanulate or 

 rotate in disposition; stamens indefinite in member; filaments long or 



