624 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVI. 



The next march to El Milleh, 14 miles from Nobat, is up the dry bed of the 

 Sailah Bileh for 7 miles, then the track leaves the bed and passes over the 

 hills to El Milleh. 



El Milleh, where there is a small blockhouse, is situated on a plain, just 

 above a dry river bed. There is a legend attached to some graves, within a 

 few hundred yards of the camp, that they belong to some sailors who were 

 shipwrecked close by. 



El Milleh to Hardeba, is a stage of 12 miles over a good track ; about 8 miles 

 from El Milleh, looking due east, two miles from the path, one sees the Fort 

 of Sulek, the centre of the late Kotaibi Operations. 



Hardeba is situated on the Saileh Hardeba, and has a good water-supply 

 from a perennial spring below the Fort. The path onwards to Ehado, the 

 next halt, a nine-mile march, is along a dry bed, which in parts is thickly 

 wooded and rather picturesque for this part of Arabia. It is exceedingly 

 unwise to encamp in the river bed during the rainy season, as mountain torrents 

 swelled by the storms in the mountains above make their appearance without 

 much warning and wash everything before them. 



Rhado brings one on the 7th evening to the foot of the D'thala hills and the last 

 march is accomplished by ascending either the Kuraba or the Robart Pass. 



D'thala, a plateau 5,000 feet, named after the village, is situated at the foot of 

 the Jehaf Range. The climate is salubrious and compares favourably with 

 Indian stations such as Poona. The weather is bracing from December to March, 

 The rainy season consisting of June, July, and August are delightful months. 

 They are characterized by frequent afternoon thunderstorms, seldom raining 

 continuously but lasting for about two hours. The average rainfall is moderate, 

 amounting to about 20 inches. 



After this short introduction, I will take up the detailed description of the 

 various mosquitoes, starting with the Anopheles. The accompanying skeleton 

 map of the Hinterland has the names of the different species marked on it. 

 It is especially intended to show the distribution of the various Anopheles 

 Mosquitoes that are found in the country. 



After examining some hundreds of specimens of the five Arabian Anopheles, 

 I came to the conclusion they were distinct species for the following reasons : — 



(1) The adult females differ from the descriptions of all the known 



Anopheles. 



(2) The eggs and larvae are distinct from any that have yet been de- 



scribed. 



Thanks to the excellent works of Captain James, I.M.S., Dr. J. W. W. 

 Stephens and Lieut. S. R. Christophers, I.M.S., on the eggs and larvae of most 

 of the Indian Anopheles, one is able to say a species of Anopheles is a distinct 

 one, if a definite difference between the eggs and the larvae of any two species 

 can be shown to exist. 



It will be noted the five Anopheles are named after different parts of the 

 country, thus enabling anyone to locate these species. 



