]18 



CHAEADEIUS. 



Africa, C. minor and its post-glacial ally C. jerdoni in India, C. placidus in China, and 

 C. nigrifrons in Australia. 



It seems probable that the ancestors of C. tricottaris met with a party of emigrants 

 from Brazil, part of the ancestors of C. vociferus, at such an early stage of their differentia- 

 tion that they coalesced, and founded a species intermediate between the two, an instance 

 of the extinction of subspecies by interbreeding, according to the theory of Menzbier. In 

 post-glacial times the three-banded Plovers of West Africa appear to have become 

 completely differentiated from those of South Africa, the former becoming C.forbesi and 

 the latter C. tricoUaris; some of which afterwards emigrated to Madagascar and became 

 C. bifrontatus. 



In a slightly different way C. jerdoni may have become partially differentiated in 

 Ceylon and Southern India, the resident birds probably breeding earlier than those which 

 migrate northwards to breed, an example of physiological isolation (miscalled by Romanes 

 physiological selection). 



GEOGRAPHICAL DISTRIBUTION 



(during the breeding-season) . 



Hiaticulce typicce. 

 C. hiaticula . . . 



Pal^iarctic Region. 



. . . North-west. 



South. 

 South-east. 



Ethiopian Region. 



West Africa. 

 South and East Africa. 

 Madagascar. 



Omental Region. 



India and Burma. 



Australian Region. 



East Australia. 



C. monachus South Australia. 



C. novjE-zelandijE New Zealand. 



Nearctic Region. 



C. semipalmatus North. 



C. vociferus . . ' South. 



C. melodus East. 



C. circumcinctus Central. 



Hiaticulce minores. 



C. MINOR. 

 . C. PLACIDUS. 



. C. FORBESI. 



. C. TRICOLLARIS. 



. C. BIFRONTATUS. 



. C. JERDONI. 



. C. NIGRIFRONS. 



