394 W. M. ADERS. 



singly. The larvae are easily recognisable by the long narrow abdomen and thorax, 

 short syphon, and the peculiar habit of gliding and not wriggling as a means of 

 progression through the water. By this characteristic they are easily singled out 

 from a mixed sample. The pupae are generally white in colour ; the abdominal 

 segments, instead of being coiled upwards towards the thorax, hang vertically 

 downwards ; conspicuous tufts of bristles attached to the anal fins are recognisable 

 with the naked eye. 



Eretmopodiies chrysogaster var. subsimplicipes, Edw. A few specimens taken with 

 and under the same conditions as E. quinquevittaiiis. 



The Mosquitos of Zanzibar and Peniha Islands. 



Anopheles costalis, Lw. This is the most abundant Anopheline in the island and 

 has been found in every district. Larvae have been captured under very varied 

 conditions, generally in small swamps and occasionally at the edges of large lakes 

 and rivers. They seem to show a marked preference for the water in the shallow 

 surface wells which are dug by the natives all over the island, this water being of 

 a distinctly milky appearance from suspended clay. Some of their rarer haunts 

 are brackish coral rock-pools, crab-holes, etc. 



Ariopheles funestus, Giles. Adults are common in native huts in outlying districts 

 in proximity to flooded rice-fields ; several have been taken in houses belonging to 

 Europeans in Pemba. Larvae are generally found in flooded rice-fields and in 

 large shallow swamps, also in backwaters of various rivers. 



The distribution of this Anopheline is nothing like so general as that of A. costalis. 



Anopheles mauritianus, Grp. Wild adults have never been captured. The 

 larvae inhabit large swamps, often in association with A. costalis and A. funestus. 

 They are easily recognised by their conspicuous abdominal banding and their habit 

 of twisting themselves into an S formation while on the surface of the water. 



Anopheles squamosus, Theo. Larvae have been taken in various large swamps in 

 association with A. mauritianus and Culex laurenti. I am unable to distinguish 

 between the larvae of this form and that of A. mauritianus. 



Stegomyia fasciata, F. As mentioned before, one of the commonest forms in the 

 town. It has been recorded from every district in the island ; several islands at a 

 considerable distance from Zanzibar are heavily infested. 



Stegomyia vittata, Big. A rare form, I have only two records of breeding places. 



Stegomyia metallica, Theo. Has been captured in various localities ; in every in- 

 stance the larvae were obtained from holes in African almond trees {Terminalia 

 catappa) and mango trees. 



Stegomyia simpsoni, Theo. Like the last-named species, found breeding in African 

 almond trees, but not so prevalent. A few were taken in an earthenware pot in 

 association with S. fasciata. 



Culex fatigans, Wied. Distributed all over the island. 



Culex invidiosus, Theo. Common in swamps in association with Anopheles costalis. 



Culex tigripes, Grp. Common all over the island. The larvae are capable of living 

 under the most varied conditions ; I have found them in swamps, old tins, water- 

 holes and in holes in trees. 



