328 Fiftieth Report on the State Museum 



have referred to is conveyed into the wound. With these two pieces 

 pressed together, a channel is formed through which the blood passes as 

 it is inunped up by the sucking-bulb, located in the head. The 

 mandibles are the most delicate of the mouth-parts, consisting only of 

 thin, linear-lanceolate blades of transparent chitin, slightly tapering in 

 their width from their base outwardly. The existence of very fine 

 serrations on their upper part (about forty-two on each) has lately been 

 announced.* 



The maxillce are tapering, transparent blades of chitin, thickened on 

 its upper edge and apparently toothed or serrated at the tip. Careful 

 observation with a powerful microscope shows them to be not serrated at 

 the edge, but the apparent teeth — about fifteen near the tip of each, are 

 really papilLx placed on the upper surface of the blade. Aided by these 

 papillae, the service performed by the maxillae is doubtless to draw 

 the other mouth parts into the skin,' as a slow gliding motion may 

 be observed in first one and then in the other as all the parts are 

 gradually buried. They are provided with muscles appropriate for the 

 purpose. 



The labium is the largest of the mouth-parts. It opens along its upper 

 side in order to receive the other parts and to serve as a sheath for holding 

 and protecting them when not in active use. When the proboscis is to 

 be inserted, it acts in this manner : Its tip, consisting of two lobe-like 

 appendages called label/cB, is closely pressed upon the surface. At once 

 it is seen to bend backward or downward at the middle, releasing the 

 contained parts — the setae— which are held firmly together as they are 

 driven into the flesh, guided and kept in place by the above named 

 labellce serving as a pair of fingers for the purpose. As they penetrate 

 deeper and deeper, the labium or sheath bends more and more until 

 when they have been buried to nearly their entire length — from having 

 been at first elbowed, it is now bent double beneath the body. 



The operation as above described is an exceedingly interesting one to 

 watch. The labium is easily recognizable in any female mosquito that 

 you will examine, appearing as a long projected beak, nearly as long as 

 the abdomen, clothed with dark colored scales, and extending in front of 

 the two delicately feathered antennae given out from between the two 

 large black eyes. 



The relative position of the mouth-organs which I have briefly des- 

 cribed, arid the manner in which they are arranged in the sheath, may be 



* American A'aturalist, xxii, 1888, p. 884. 



