PKOBOSCIS OF MALE 43 



males have been distinguished from the females, by all scientific entomological 

 writers on the subject, by means of their feather-like antennae and maxillary 

 palpi. 



" The proboscis of the male of Culex pipiens, the only species the male of 

 which I have studied, is slightly longer and slenderer than the corresponding 

 organ in the female. The setae are fewer in number and less completely sheathed 

 by the labium than in the female ; they consist of a well-developed labrum-epi- 

 pharynx and two slightly developed maxUlse, The mandibles are absent, and 

 the hypopharynx coalesces with the labium (fig. 13 h and I). The labium and 

 maxillary palpi are more densely covered with hair and scales than they are in 

 the females, and they contain muscles ; the other mouth-parts, the setae proper, 

 are naked, chitinous, and contain no muscles. In comparative length the mouth- 

 parts may be arranged, longest first : maxillary palpi, labium and labrum-epi- 

 pharynx, maxillae ; — in comparative size they may be arranged, largest first : 

 labium, maxillary palpi, labrum-epipharynx, maxillae. The relative position of 

 the mouth-parts of the male is different from that in the female (compare figs. 

 8-9 with 13-15) in that the short, rudimentary maxillae are pushed out sidewise 

 to allow the hypopharynx to coalesce with the labium. In the male the oesoph- 

 ageal pump, or bulb behind the nerve-ring, fails, and the sucking of fluids 

 must be done by the pharynx alone, as it is done in most diptera. 



" The labrum-epipharynx is nearly the same in general form and structure in 

 the male Culex as it is in the female, it is a trifle longer and slenderer, but the 

 same figures (5, Ir-e, and 6)will serve for the tips of both. In section (fig. 12, 

 Ir-e), the labrum shows a groove on its upper surface, which deepens as it nears 

 the base (fig. 13, Ir-e). The apical four-fifths of the labium contains no other 

 seta than the labrum-epipharynx, as seen in fig. 12, which is a section at about 

 the middle of the proboscis. At the base of the labrum-epipharynx are pharyn- 

 geal muscles similar to those found in the female, and with similar insertions 

 and origins, except that the median muscle (fig. 15, pm') is not divided into 

 three parts as in the female (fig. 9, pm') . 



" The hypopharynx is, throughout its whole length, joined to the labium, and 

 thus necessarily pushes the maxillse, which would normally lie between it and 

 the labium, to one side, (See fig. 13, h and mx.) The hypopharynx shows, in 

 section (fig. 13-15, h), the same chitinous rod through the middle as in the 

 females, but I was unable to detect any channel for saliva through this rod. 



" The maxillae are very thin lamellae of transparent chitin, about one-fifth as 

 long as the labium, and so delicate as to be easily overlooked. Although as broad 

 at the base as is the tube of the epipharynx, they taper regularly from their base 

 to their fine tips. 



" The maxillary palpi are five-jointed, very hairy toward the tip, much longer 

 than they are in the female, and when at rest their basal portions cover the 

 labrum-epipharynx and maxillae in the sheath of the labium. 



" The labium of the male Culex is similar in general structure to that of the 

 female, if one considers it together with the hypopharynx. It is, however, 

 slenderer, more densely covered with scales, has a shallower groove for the recep- 

 tion of the labrum-epipharynx, and has a joint near the middle. The slender- 

 ness of the labium in the male extends itself to the labellfe. (Compare fig. 4, lb, 

 with fig. 3, Ih). The groove of the labium of the male increases in shallowness 

 from tip to base; at the middle of the proboscis (fig. 12) it is so shallow that it 

 fails to fully protect the labrum-epipharynx, and at its base (fig. 13) it is so 

 shallow that the other mouth-parts rest only on top of the labium. To make up 

 for this deficiency of protection by the labium, the maxillary palpi, as was pre- 

 viously mentioned, cover over the upper side of the enclosed parts (see fig. 13), 

 and thus, although free from the labium, fonn a part of the protective sheath, 



