CULICID FAUNA OF THE ADEN HINTERLAND. 627 



water from the well. The Hardeba water was kept quite separate. This then 

 explained the presence of the few females which were caught every morning. 



At Hardeba it breeds in the spring water and many pools which collect in the 

 river bed, chiefly from March to November. 



It breeds in all the wells around D'thala from May to the end of October. 

 It was also found in two springs near D'thala. Towards the middle of October 

 at D'thala most of the adults bred out of larvae were very miniature and I feel 

 certain that if these specimens had been sent to the British Museum for identi- 

 fication they would have been labelled differently. They had hardly any palpal 

 markings and the wing fields were quite pale. This seasonal variation Avas 

 observed in the earlier part of the year when this anopheles begins to come into 

 season. 



It was at D'thala that this mosquito was dissected and sporozoits were found. 



When on a short visit to Am Riga in the Subahai country this anopheles 

 was found breeding with Culexpipiens in brackish water. 



This anopheles was never found by me in Aden, but Dr. Young of Sheik 

 Otharaan informed me that he once observed an anopheles mosquito at Steamer 

 Point, which was most probably, he thought, arabiensis. I am certain this 

 mosquito will be found in the wells both at the Crater and Steamer Point and 

 that it has made its way into Aden from Sheik Othaman. When stationed in 

 Aden a short time I undertook to estimate the endemic index and soon found 

 malaria parasites in children who were born in Aden and who had never been 

 out if it. 



This anopheles is closely related to A. rossii and A. ludlowii, but there 

 are some important differences, which will be seen on comparing them. Speci- 

 mens of this mosquito were sent to Mr. Theobald in May 1904 and they were 

 said to be .4. ivellcomei, Theobald. Since then I have read the description of 

 A. ivellcomei in the First Report of the Gordon Memorial College and it is 

 obvious to me that they are not the same. I sent some specimens to 

 Dr. Stephens, saying Mr. Theobald thought they were A. ivellcomei. He 

 compared them with the type in the British Museum and he informed me they 

 were quite distinct. 



Curiously enough though Mr. Theobald informed me that this mosquito was, 

 in his opinion, A. ivellcomei, yet in a note on A. pharceusis he says, "it also 

 extends into Arabia, having recently been sent me from the Aden Hinter- 

 land." This note is obviously meant for A. ivellcomei as up to that time 

 (September 1904), when the report first appeared, this was the only anopheles I 

 sent to Mr. Theobald. It is hardly necessary to say not a single specimen of A. 

 pkarceusis was found by me anywhere in the Hinterland. 



Anopheles dthali n.sp. 



Palpi pale with two white bands, thorax light brown covered with curved 

 scales. 



Abdomen greenish with darker patches in parts. Legs brown with yellowish 

 bands at the joints. 



