336 BANKS. 



over two weeks and including the rice fields, which were flooded at this 

 time of the year, the water tanks near buildings, the streams, the wells, 

 and in fact all probable breeding places revealed no other species of 

 Anophelince. 



GEOGRAPHY AND TOPOGRAPHY. 



The town of Cervantes is situated near the center of the subprovince 

 of Lepanto. It lies at an altitude of 508.8 meters upon a north-south 

 hill 60 to 80 meters high between, and south of two forks of the Abra 

 Eiver. Each of these forks flows through a rather flat valley which 

 favors the wandering of the streams from their habitual channels so 

 that in reality from about 1 kilometer above the town to approximately 

 a kilometer below there are, in the bed of each fork, four or five sub- 

 parallel streams running more or less obliquely to the main course of 

 the river as shown on Map 1. The entire river bed is covered with 

 rocks of various sizes, some of which are sufficiently large to impede or 

 change the course of the stream during the dry season. 



The hill upon which Cervantes stands is composed of primitive rock 

 of which the principal constituent is diorite with a more or less eroded, 

 clayey, top soil. The base of this hill is cut into small, sharp gullies by 

 the action of the water during the rainy season and in many of these 

 gullies during the dry period there are springs, usually with a very 

 small and slow flow. Algce, upon which the mosquito larvae feed, ac- 

 cumulate upon the wet rocks in these springs. 



This entire valley lying between the Cordillera Central and the Cor- 

 dillera Occidental has but one outlet to the sea, namely through Abra 

 Pass, which is north of Cervantes. The mountains to the west average 

 1,000 meters in height while those to the south reach an elevation of 

 2,200 meters. 



The town of Sagada lies 17 kilometers northeast of Cervantes at an 

 altitude of 1,445 meters, on the east side of the Cordillera Central and 

 in a region of limestone formation. A number of small streams and 

 springs are found in its vicinity and some of these are subterranean. 



Bontoc, 8.5 kilometers due east of Sagada, in the subprovince of 

 Bontoc, has an altitude of 842 meters and lies on a slightly elevated 

 bluff on the Anguinak Eiver (Baduyan or Cagayan). 



The valley through which the Anguinak flows in the region of Bontoc 

 is narrow south and southwest of the town, but widens east of it, allowing 

 the river to divide into several streams during the dry season, but during 

 the rainy period making it a wide, impassable current. There are a 

 number of islands in the stream below the town during the dry season, 

 several of which are shown on Map 2, and one toward the northeast. 

 These islands have practically the same formation as the ones in the 

 inner bed at Cervantes and facilities of the same character, but in less 

 degree, are offered for the breeding of Myzomyia ludlowii Theob. 



