PROGNE. 329 



Genus PROGNE Boie. 



Proqne Boie, Isis, 1826, p. 971. Type P. purpurea (Linn.). 1766= 

 P. subis (Linn.), l7o8. 



Fig. 131 — To show the form of the tail. 



This genus contains the largest of the Swallows. The bill is 

 depressed at the base, the width being about four-fifths the length 

 of the exposed culmen ; the nostrils are without any superior mem- 

 brane, rounded, and exposed. The wing is pointed and nearly 

 twice the length of the tail. The feet are strong and the claws 

 sharply curved ; the middle toe and claw are about one-third longer 

 than the tarsus. Coloration: male and female similar. 



Key to the Species. 



A. Upper surface purplish blue. 



a. Larger, wing more than 140 mm. ; ab- 

 domen purplish blue P. suhis, p. 330. 



l. Smaller, wing less than 140 mm. ; ab- 

 domen white P. chalyhea, Tp. ZKl. 



B. Upper surface smoke-brown P. tapera, p. 342. 



