632 MOSQUITOES OF NORTH AMERICA 



verse, pointed. Both pairs of dorsal head-hairs single, rather long; ante- 

 antennal tufts multiple. Mental plate triangular, rounded at tip ; central tooth 

 rounded, with eleven on each side, the first four short and rounded, the succes- 

 sive ones more pointed and more remote. Mandible quadrangular, elongate ; a 

 patch of small spines at base ; four filaments near tip, two large and two small 

 feathered ones ; an outer row of cilia from a collar ; nine filaments on outer edge, 

 the two nearest collar feathered; dentition of four teeth, the outer long; two 

 short and two long processes before, a group of minute ones at base, a broad 

 serrate filament and three slender ones within; three spines below, then the 

 cleft-furcate process with scattered hair-tufts ; three large setae within ; a promi- 

 nent angle below, a row of long hairs at base. Maxilla elongate hemispherical, 

 divided by a suture ; inner half densely haired ; a large tuft at apex ; outer half 

 with hairs at tip and two filaments near suture; palpus three times as long as 

 wide, appressed to maxilla, four small digits at tip. Thorax rounded, wider 

 than long; hairs abundant, but not long, the pro thoracic subdorsal ones mul- 

 tiple. Abdomen moderate, the anterior segments shorter, segments 3 to 7 

 dorsally with transverse rows of minute spicules; lateral hairs triple on first 

 four segments, double on fifth and sixth. Tracheal tubes broad, band-shaped. 

 Air-tube moderate, about three times as long as wide ; peeten dense and evenly 

 spaced, running to near middle of tube, followed by a multiple hair- tuft; single 

 tooth a long spine with broad base and three to five basal branches. Lateral 

 comb of eighth segment of many scales in an elongate patch ; single scale broad, 

 with fringe of long spinules, the central ones equal, none differentiated. Anal 

 segment longer than wide, with a large dorsal plate reaching halfway down the 

 sides, slightly emarginate at sides ; dorsal tuft a hair and brush on each side ; 

 ventral brush well developed, a few tufts preceding barred area. Anal gills 

 very short, bud-shaped. 



On the flat marshes of the Pacific coast the larvae of the race quaylei occur in 

 pools of salt water left by high tides. A set of larvae appears after each high tide. 

 Mr. Quayle has published the following : 



" The eggs of this species are laid, so far as our observations go during the 

 past year, in the mud of pools which are formed by the monthly high tide, and 

 which dry up before the succeeding high tide reaches them. This was demon- 

 strated several times during the season by taking mud from such pools and sub- 

 merging it with ordinary sea water, when the wrigglers would appear in from 

 three to four days. Another method of determining this egg-laying habit con- 

 sisted in sinking ordinary soap boxes, the bottoms first being removed, to a 

 depth of two or three inches in the mud of pools where larvae were likely to 

 appear. These boxes were thoroughly screened on the top to prevent any pos- 

 sible entrance of adults, and were kept from floating away with the high tides by 

 means of stakes driven into the ground. When the high tide reaches the pool 

 the mud inclosed by the box would be covered with water through seepage from 

 below, the box being high enough to allow no water to enter at the top, thus 

 allowing no possible chance for the eggs to be deposited in the water. In a few 

 days larvae would appear in the box in as great numbers proportionally as in 

 the pool outside the box. This egg-laying habit was further verified by the fact 

 that throughout the season there were no instances recorded where larvae 

 appeared in permanent pools, or, at least, where there was not a perceptible low- 

 ering of the water, where eggs could be laid at the borders 



"Larvae in the smaller pools appeared more abundantly each month until 

 June, despite the fact that no adults were seen in the vicinity during the present 

 season. This can be accounted for only through the fact that ihe eggs which were 

 laid during the previous season did not all hatch with the high tides of early 

 spring, the great majority not appearing until the higher temperature of May 

 and June. 



