THE LARVAE OF MALAYAN ANOPHELES. 



171 



The only microscopic character by which these larvae may be difierentiated is 

 the form of the innermost of the submedian anterior thoracic hairs (fig. 3). In 

 sinensis this hair has a long simple stem, which is seen when highly magnified to be 

 branched near the end. This minute difference has proved to be constant in a large 

 number of specimens of cast larval skins which have been examined. Other larval 

 characters in which it has been alleged that differences exist between sinensis and 

 barbirostris have been found to be identical in the two species. 



12. Anopheles tessellatus, Theo.^ 

 Average length at maturity 4*0 mm. 



Head : Anterior dypeal hair. Inner hair stout , of medium length, with minute 

 lateral branches ; outer hair short, only about one-fifth the length of the inner, 

 simple. Posterior clypeal hairs short, slender and simple. Occipital hairs short, 

 both branched. 



Thorax : On the posterior quadrant a rudimentary stellate tuft composed of five 

 to seven narrow lanceolate leaflets. 



Abdomen : Segments iii.-vi. carry fully developed stellate tufts composed of 

 leaflets with ill-defined filaments. On segment vii. the leaflets are narrowly lanceolate, 

 without filaments. The average length of the leaflets on the mid-abdominal segments 

 is 0*06 mm. The average relation of length of filament to total length of leaflet is 

 as 1 to 3. The indentations at the base of the filament are minute and the filament 

 tapers gradually to a point. 



13. Anopheles umbrosus, Theo. (fig. 15). 



Fig. 15. Anopheles umhrosus, Theo. 



Average length at maturity 5*0 mm. 



Head : Anterior clypeal hairs. Inner hair long, simple ; outer hair with few 

 branches as compared with the allied species sinensis and barbirostris ; the usual 



* See also Bull. Ent. Kes., iv., p. 129 (1913). 



