462 



THE AMERICAN NATURALIST [Vol. XL 



59 genera belonging to 19 families, 6 of which are Monocotyledons. 

 The INIonocotyledons are: one genus of INIayacacese, six of Rapa- 

 teacese, two of Commelinacese, one of Pontederiacese, five of Lili- 

 acese, four of Amaryllidacese. The Dicotyledons are: one genus of 

 Pittosporaceffi, nine of Leguminosae, three of Tremandracese, four of 

 Sterculiaceffi, eleven of Ochnacese, two of Dipterocarpacefe, one of 

 Flacourtiacese, sections of Begonia in Begoniaceae, sections of Ardisia 

 in Myrsinacese, one of Loganiacese, two each of Gentianaceje Solan- 

 aceae, and Rubiacese. The table for the Solanum-Cassia type shows 

 a maximum for the Tropical American Region, with the Australian 

 Region second. Genera of visitors observed on flowers of this type 

 are; bees — Osmia, Megachile, Ceratina, Xylocopa, Euglossa, Bom- 

 bus, Apis, Trigona, Melipona, Halictus, Augochlora, Megacilissa, 

 Melissodes, Podalirius, Centris, Oxaa; flies — Rhingia, Volucella; 

 butterflies — Argynnis; birds — Mimus, Nectarinia, Chlorostilbon. 



The melastomataccous type difl'ers from the preceding mainly in 

 the long filaments and in both locules of the anther usually opening 

 through a single pore. Of the 161 genera of INIelastomatacese it 

 includes all except 12, besides one genus of Leguminosge and two of 

 Bixacese. The Tropical American Region contains about 63 % of 

 plants of the melastomataccous type, the Indian Region showing 

 about 20 %. The observed visitors are: bees — Xylocopa, Bombus, 

 Trigona, Halictus, Centris; flies — Syrphidse; beetles — Cetonia, 

 Buprestis; birds — Trochilida;. 



The table of genera of the three types shows a Tropical American 



Apidje the Tropical American Region is first, witli (\ \ genera of bees, 

 the IMediterranean-Oriental Region srcond, witl. xhr Xorthern 

 Region third, with 50. Table J shows the di^triluition of llynienop- 

 tera of all genera. K show s the relative abundance of genera of Apidfe. 

 Diagram L gives curves for the distribution of endemic genera of the 

 apically dehiscent types, of the Phanerogamia, of the Apidse, and of 

 all Hymenoptera. Diagram M shows the relative distribution of all 



C. Robertson 



