26 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 139 



preceding spiracle, but as independent branches from a persisting 

 spiracular atrium, it is perhaps possible that the pupal trumpets are 

 in this manner related to the "notched organs" of the larva. Chang 

 and Richart contend that the latter serve to keep the anterior part of 

 the Anopheles larva afloat while feeding at the surface, but experi- 

 ments have shown that the organs can be cut off without any apparent 

 effect on the suspension of the larva (Jones, unpublished obser- 

 vations). 



THE ABDOMEN 



The larval abdomen (fig. 10 G) appears to have only nine segments, 

 and it is usually represented as nine-segmented, with the respiratory 

 apparatus on the eighth segment and the terminal segment enumerated 

 as the ninth. However, there is reason for believing that a true ninth 

 segment is combined with the eighth. Christophers (1922) con- 

 tended that though "much of the apparent eighth segment is actually 

 this structure, the greater part of the spiracular apparatus must 

 be assigned to the tergite of a hitherto unrecognized ninth abdominal 

 segment." Convincing evidence of this interpretation is the fact that 

 the rudiments of the male genitalia are formed beneath the larval 

 cuticle at the base of the terminal segment, and that in the adult male 

 the genital claspers are carried on the posterior margin of a small 

 but distinct ninth segment (fig. 27 B). Though this segment is not 

 evident as a distinct annulus in the larva, it must be represented by 

 some part of the apparent eighth segment immediately anterior to the 

 genital rudiments. In the pupa, as will be shown (fig. 16 D,E) a small 

 ninth-segment ring (IX) lies behind the eighth segment and carries 

 the tail fins and the small anal lobe. The anal segment of the larva 

 (fig. 10 B) must therefore be the tenth, as it is in the pupa and the 

 adult. 



The fully segmented abdomen of the mosquito embryo is shown by 

 Telford (1957) in Aedes and by Menees (1958a) in Anopheles to 

 have 10 segments. Telford says the tenth segment, or telson, dis- 

 appears with the ingrowth of the proctodaeum, but since a tenth seg- 

 ment is present in the adult, the "telson" must be an eleventh segment. 

 In some larvae, as seen in Mansonia (fig. 11 A) a small lobe (XI) 

 protrudes from the end of the tenth segment, which would appear to 

 be the evaginated anus-bearing telson. Even in the embryo, then, 

 the ninth segment is not differentiated from the eighth. It appears as 

 a distinct ring first in the pupa and as a definite segment in the adult. 



The first seven segments of the larval abdomen have no distinctive 

 features, except that in Anophelini (fig. 9 A) the last five or six of 



