THE DEHISCENCE OF ANTHERS BY APICAL PORES. 235 



Of the Monocotyledons one family, the Rapateaceae of 6 

 <*enera, is endemic in tropical South America. Mayaca 

 has 8 of its 10 species there. Of the two apically dehis- 



in which dehiscence by 



cent 



Commelinaceae, the genus 



mostperfect is endemic in tropical South Amer 



In the 



\ 



& 



as is also the highly interesting Cocldiostema. 

 Liliaceae and Amaryllidaceae, 4 of the 8 apically dehiscent 



mera are endemic in extratropical South America. 



Thus, 11 of the 19 genera of the Monocotyledons are 

 endemic in South America and another has 8 of its 10 



species there. 



Turning now to the Dicotyledons, we find that of the 40 

 genera, 11 are endemic in South America and 7 others occur 



there. 



In the Monocotyledons, then, 57.8 per cent of the 



o-enera are endemic in South America, another has 8 of its 



10 species there, while the two others may possibly have 



been derived from the same region; 63.1 per cent of the 



apically dehiscent monocotyledonous genera occur in South 



A 



Among the Dicotyledons, we have 27.5 



per 



cent endemic in South America and 7 more genera have 

 some of their species, and in five cases the most of their 

 species, in South America. Together, 18 of the 40 apically 

 dehiscent genera of Dicotyledons are represented in South 



America, or 45 per cent. 



Taking both Monocotyledons and Dicotyledons, we have 



i assigned to this type represented in 



gener 



South Am 



These genera contain from one to over nine hundred 

 species; in some, all of the species are apically dehiscent, 



Begoni 



Ardi 



of about 200 species, only a few species are apically 

 dehiscent. To this question of the geographical distribu- 

 tion of species, we shall recur later. Here we may merely 

 note that Solarium has about 700 of its 970 species in 



* 



