354 THE CANADIAN ENTOMOLOGIST. 



that cross-fertilization is advantageous to the species, and that as a 

 consequence close adaptations to certain agents well fitted to effect cross- 

 fertilization have been evolved, it becomes at once evident that there will 

 be an intimate correlation between the distribution of the plant and the 

 agent upon which it depends for fertilization. This fact was recognized 

 many years ago, and numerous attempts have been made to determine the 

 effect of the insect fauna upon the constitution of the flora. Several of 

 these investigations, especially those employing the statistical methods 

 developed by Miiller, have yielded results of great interest. 



This phase of ecology is clearly one which demands for its complete 

 development the co-operalion of students of both sciences, and it is the 

 purpose of the present paper to present briefly some results which seem to 

 the writer to indicate the interdependence of certain phases of floral 

 ecology and entomology and the importance both to botany and zoology of 

 their investigation. 



Some years ago, while studying the floral ecology of Solatium and 

 Cassia, the writer was much impressed by the similarity of the floral 

 structure of these systematically widely-separated genera and the identity 

 of their ecological relations. Both genera are characterized by a widely- 

 open perianth, elongate anthers basifixed on short filaments and opening 

 by apical pores and usually connivent around a filiform style, terminating 

 in a punctiform stigma. Upon examining the systematic literature it was 

 found that forms in which the anthers open by apical pores, instead of the 

 more common longitudinal slits, are characterized by stamens and perianth 

 of the same form as those of these two genera. Certain genera from such 

 systematically widely-separated families as the Liliaceae, Pontederiaccce, 

 Commelinaceae, Pittosporacese, Leguminosse, Tremandracese, Solanaceae 

 and Rubiacese, and genera from some other groups, have a floral structure 

 conforming in a remarkable degree to that exemplified by the familiar 

 So/anum and Cassia. The floral structure in these families exhibits a 

 wide range of form, and the close resemblance of these representatives, 

 amounting to an almost identical habit, suggested the interest of a further 

 investigation which might furnish some clue to the real nature of the 

 parallelism. Solanum and Cassia are known to be adapted to pollen- 

 collecting bees, and as the material and literature were examined the 



evidence that all the forms are adapted to fertilization by bees became 

 quite considerable. It was also observed that these apically dehiscent 

 forms seemed to be more abundantly represented in some regions than 

 in others. 



