PLATE V 



Figure 1. The sucking apparatus of Tabanus, schematic, in 

 profile, e.b.c., a muscle with a fine tendon, attach- 

 ed to the cornua of the buccal cavity on each side. 

 These probably draw up the cavity, and with it the 

 epipharynx and the hypopharynx, while the mandibles 

 and maxillae are in action, sph., sphincter muscle, 

 c.p., compressor muscles, which assist in returning the 

 walls of the pharynx to a position of rest. e.L, ele- 

 vator muscle of the labrum, by which the size of the 

 prestomal opening is regulated, p. ph., protractor 

 muscles of the buccal cavity, acting probably in 

 opposition to e.b.c. r.oss., retractor muscle of the 

 oesophagus. Note that the pharynx is anterior to the 

 brain, while in the mosquito it is mainly posterior, 

 x 40 about. 



Figure 2. Transverse section through the head of a mosquito, to 

 show the arrangement of the plates of the pharynx, 

 l.d.ph., the lateral dilators. 



Figure 3. The labium of Haematopota, seen in profile, in a 

 cleared preparation, a.g., the groove in the anterior 

 surface in which the piercing stylets are concealed. 

 The membrane, mb., is continuous with that of the 

 gular region, x 54. 



Figure 4. The distal end of the maxilla of Tabanus, to show the 

 teeth, x 650. 



Figure 5. The sucking apparatus of Joblotia, a large mosquito. 

 f.c., a flange projecting inwards under cover of the 

 clypeus, to which is attached a muscle, mu., probably 

 regulating the size of the prestomal slit in the act of 

 sucking, by lifting up the labrum. t, the chitinous 

 tube which passes through the brain and connects the 

 buccal cavity and the pharynx, f., a chitinous flange 

 providing attachment for the muscle which works the 

 salivary pump, x 90. 



