hungerford: aquatic hemiptera. 163 



Second iTtstar. 



"Form as in the first stage, perhaps a little less broad in proportion 

 to the length. Rostrum as before, except that it is perhaps a little less 

 stout. Antennas still blunt, short and stout, but not so club-shaped. 

 They now begin to show two equal joints. The legs as before, the first 

 pair not quite so broad proportionally, with the blunt apical femoral 

 tooth beginning to show as an undulation in the inner side of the femur. 

 The tibiae of the second and third pair are better provided with spines, 

 which increase in number distally. The terminal combs very apparent. 



"Size: Long., 13 mm.; lat. not measured, dimensions being taken from 

 moulted skins. 



"Air-tube, 2.7 mm." 



Third Instar. 



"Form, not greatly changed from the preceding instars, except for 

 slight variations in proportions. 



"Rostrum, much as before, but a little slimmer. In this instar the 

 tactile hairs at the extremity of the proboscis are quite noticeable. 



"Antennae appear imperfectly three-jointed in this instar. The suture 

 separating the basal joint is quite noticeable, and that between the second 

 and third joints shows as an incision in the outer margin of the antennas, 

 from which a little impressed line goes about half way across. Below 

 and above this indentation are two prominences, the beginning of the lobes 

 of the segments. Both prominences are ai'med with a stout spine, that 

 of the third joint being about twice as thick as that of the second. The 

 third joint appears to be pitted at the rounded end. 



"Thorax much narrower, distinctly trisegmentate. Head closer to the 

 adult shape, the eyes flattened on the inner side, and quite prominent. 

 The wing-pads first appear in this instar, though very small and rudimen- 

 tary. 



"Legs and tarsi as before, with the spines of the second and third pair 

 of tibi« stronger, and the tibial comb more developed. In this instar the 

 fringing hairs of the second and third appear, scattered on the femora 

 and sparse on the tibiae, but quite long. 



"The false stigmata are quite noticeable at the sides of the abdomen, 

 as darkened spots in the integument. The legs are now shorter than the 

 length of the bug, and reach but little beyond the extremity of the respira- 

 tory tube. The first pair are not quite as broad proportionally as in the 

 previous instars, and show the same undulations of the femora where the 

 second tooth will be. 



"Size: Long, (extremity of the rostrum to end of siphon), 19 mm.; 

 lat., 1.4 mm.; air-tube, long., 4 mm." 



Fourth lyistar. 



"Form as before. Rostrum but slightly changed. 



"Antennae evidently three-jointed, the prominences more developed, and 

 the several spines on the third and second segments quite evident. 



"Legs and tarsi as before, with the peculiarities more accentuated. 

 They extend only a litle beyond the siphon, and are therefore not as long 

 as the body by the length of the thorax. 



"Colour more or less mottled, with banded legs. General tint grayish. 



"Size: Long., 30 mm.; lat. (not taken, specimen being only a cast skin 

 in this instar) ; air-tube, long., 7 mm." 



Fifth Instar. 



"Form elongate as in the adult. Head, including eyes and exclusive 

 of rostrum, broader than long. Rostrum as before, but nearer the adult 

 shape. The second joint begins to show the basal constriction so notable 

 in the adult. 



"The rostrum is shorter than the length of the head. Eyes trans- 



