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muscles of the labium, for, during the process of extracting the setae from the 

 skin, while they are slowly sinking back into the groove upon the upper side of 

 the straightening labium, the mosquito keeps the labellae pressed firmly upon 

 the skin. Reaumur described carefully, in his memoir, the process of biting in 

 Cule.r, and was the first, probably, to describe and figure how the insect disposed 

 of its labium during the operation. 



The mouth-parts of Cule.r, as* above described, are suspended under a clypeus, 

 or epistom, which is figured from the side in fig. 1, c; from above in fig. 2, c; 

 in length-section in fig. 11, c; and in cross-section in fig. 9, c. This clypeus is 

 the hood-shaped forward continuation of the lower part of a A -shaped piece of 

 chitin which forms the framework of what may be termed the "face" of Gulex; 

 right and left of the upper portion of this framework pass out the antennal 

 nerves, the antennae being supported by the framework itself. 



The pharynx (fig. 11, p), the tubular continuation of the epipharynx above 

 and the hypopharyux below, as it passes backward, beneath the centre of the 

 A -shaped framework, turns somewhat upward, is narrowed to the valve prev- 

 iously described, then widens slightly again, and, as oesophagus (fig. 11, oe) 

 passes through the oesophageal nerve-ring, in which it is supported by three 

 delicate chitinous rods, which lay, one longitudinally on its ventral surface, and 

 two to the right and left on its dorsal surface. Just posterior to the oesophageal 

 nerve-ring, directly above the nerve-commissure which connects the infraoesophageal 

 ganglion with the first thoracic ganglion, the oesophagus suddenly expands into 

 an oesophageal pump, or bulb, the longitudinal section of which is shown in 

 fig. 11, ft; the cross-section in fig. 10, b. This bulb, which is the chief sucking- 

 organ in the female Cnh'.r, is supported b three longitudinal chitinous rods, which 

 are stouter continuations of the three rods supporting the oesophagus through 

 the nerve-ring. These rods (fig. 10, r) have between them chitin-plates (fig. 10, 

 which are suspended from the rods by elastic membranes. On the dorsal plate 

 is inserted a double muscle, or a pair of muscles (ft*//), the origin of which is 

 in the dorsal part of the chitiuous shell of the head. Each of the lateral plates 

 has inserted on it a muscle (bm'), the origin of which is in the chitin of the 

 lower lateral regions of the head. The origin of each of these muscles is in the 

 so-called occipital region of the head, that is, behind the eyes. By the simul- 

 taneous contraction of these muscles (bm and ftw'), the lumen of the oesophageal 

 bulb is enlarged, and the blood flows into the bulb from the pharynx, and, 

 upon their relaxation, the elasticity of the chitinous walls of the bulb drives the 

 blood, which cannot return to the pharynx because of the closing of the valve 

 at v (fig. 11), into the stomach. 



