these are the ones that penetrate the skin in biting, are not jointed; the labium 

 of the female Cidex is not jointed throughout its length, but the lobes, or 

 labellae (Fig. 3 and 4, ll>), are jointed to it, by a true joint, near its tip; the 

 maxillary palpi are sometimes four-jointed, sometimes five-jointed, probably varying 

 according to the species. Unlike the mouth-parts of most diptera, those of 

 Cidea; with one exception, are free to the base ; this exception is that the labrum 

 and epipharynx are united their whole length, forming a piece, which is shown 

 in section in fig. 6, d. The labium and palpi are the only mouth-parts which 

 contain muscles. The epipharynx forms the channel through which Cidex sucks 

 up blood ; the hypopharynx probably furnishes a channel for the discharge of a 

 saliva-like fluid. A pumping organ, trianguloid in cross-section (fig. 10, />), for 

 sucking up blood into the pharynx, is formed by a dilation of the oesophagus 

 behind the oesophageal nerve-ring. Each of the above parts will be described 

 more in detail later. In comparative size and strength the mouth-parts would 

 be arranged as follows, the largest and stoutest first: labium, labrum-epipharynx 

 (the name by which I shall designate this compound piece), hypopharynx, maxillae,' 

 and mandibles. 



The general arrangement of the mouth-parts, relative to each other, is shown 

 best in fig. 8, which is of a cross-section through the middle of the proboscis 

 of a female Cule.r rufus, while in repose, with the setae sheathed in the labium. 

 The labium (7), clothed on the outer side with its scales and hairs, wraps itself 

 nearly around the other mouth-parts. In it lay the two maxillae (w.r), partly 

 enclosing the parts above them, and thus helping to bind the parts together; 

 above the maxillae are the two mandibles (m), and immediately above the man- 

 dibles, in a median line, is the hypopharynx (/*), with a thickened middle 

 portion. Resting on the hypopharynx is the labrum-epipharynx (/-> artd <>) ; 

 the epipharynx is omega-form in section, and above it, delicately attached, is 

 the labrum. The determination of the positions of the hypopharynx, mandibles 

 and maxillae, in a section, is difficult, because of their minuteness and 

 transparency, and because that they are very closely packed together, much 

 more closely, relatively, than they are represented in figure 8. Their 

 position was finally determined by the following process, which I repeated 

 several times to insure accuracy. The section of the proboscis, still in the par- 

 rafine in which it was cut, was put on a microscopic slide, covered with a 

 cover-glass, and a piece of blotting-paper laid at that side of the cover-glass 

 toward which the labium was turned. Then, while watching the parts carefully 

 with the microscope, turpentine was passed under the cover-glass, at the side 

 opposite the blotting paper, and allowed to flow slowly about the object until it 



