ILLUSTRATIONS. 



Map 1. Sketch of northern Luzon showing Cordilleras Occidental and Central 

 with the courses of the Abra and Cagayan Chico Rivers. 



2. Town of Cervantes and vicinity showing character of Abra River bed at 



this place. 



3. Towns of Sagada and Bontoc, showing character of Cagayan River bed 



near Bontoc. Note the great width of the river south and northeast 

 of Bontoc. In the dry season the river channel breaks up into a series 

 of small streams which make ideal breeding places for Myzomyia hid- 

 lowii Theob. This condition is worse at Cervantes than at Bontoc. 

 Plate I. Dam in the Cagayan Chico River near Bontoc with a view of the island 

 below it and the streams which traverse the island. Bontoc lies 

 around behind the hill at the left. 

 II. Cagayan Chico River, showing a characteristic spot favorable to the 

 breeding of mosquitoes. The Abra River at Cervantes is of the same 

 type. 



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