776 



THE DIPTERA 



may be evolved during the next few years, as there are already signs 

 that such a system may be possible. 



Careful dissections of Anopheles have been made by Nuttall and 

 Shipley, and of Culex by Christophers, while the larva and pupa of 

 Anopheles have been studied in detail by Tmms. 



As the Anopheles is, without doubt, of the greatest importance 

 to medical men, its anatomy will be described. ^ 



Fig. 380. — Transverse Section 

 OF THE Proboscis or Ano- 

 pheles maculipennis Meigen. 



(After Nuttall and Shipley, from 

 the Journal of Hygiene.) 



I, Labium; 2, maxilla; 3, 

 hypophar^mx, with salivary 

 duct; 4, mandible; 5, labrum- 

 epi pharynx with the figure (5) 

 placed in the blood-tube. 



Fig. 381. — Distal End of the Proboscis 

 OF Anopheles maculi tennis Meigf.n. 



I, Labium; 2, labellae; 3, labrum- 

 epi pharynx; 4, maxillae; 5, mandibles; 

 6, skin line. (The labellce should be diver- 

 gent to the plane of the paper.) 



Morphology. — Anopheles maculipennis Meigen has been studied by Nuttall 

 and Shipley, whose account is followed in the description given below. 



The body of a mosquito is di\dded into [a) head, {h) thorax, [c) abdomen. 



Head. — The most conspicuous objects on the head are the two large 

 reniform, often brilliantly coloured eyes, which lie on a piece of exoskeleton, 

 called the ' epicranium,' which covers the whole head, except in the ventral 

 median line, where the gula can be seen. Dorsally the eyes nearly meet, being 

 separated by a space called the ' vertex,' in front of which is the frons, which 

 carries a pair of antenna?, different in male and female. The male antenna 

 has sixteen segments, of which the first segment is very small; the second is 

 globular, and contains an auditory organ; the third is long, and the fourth 

 to the fifteenth carry twenty- five to thirty hairs in whorls at the proximal end 

 of each segment. The sixteenth segment is about half as long as the penulti- 

 mate. So dense are the whorls of verticillate hairs in the male that the term 

 ' plumose ' is applied to the whole antenna. The base of the sixteenth seg- 

 ment carries six hairs, and the tip is rounded. The female antenna consists 

 of fifteen segments. The first is very small, merely a ring of chitin ; the second 

 is deeply hollowed for the third segment, which is the longest. The proximal 

 ends of the fourth to the fifteenth carry six large hairs. The tip of the 

 fifteenth segment bears fine hairs. These few hairs produce quite a different 

 appearance in the antennae, which are called ' pilose,' 



In front of the frons a sclerite called the ' clypeus,' belonging to the exo- 



