60 [March. 



in the middle ; femora reddish ; first two pairs of tibiae pale yellowish, 

 hind pair dark reddish-brown in the middle, becoming paler at base and 

 apex ; tarsi two-jointed, basal joint very small, brownish, second joint 

 long and pale with apex fuscous ; claws long, brownish at base, becoming 

 pale outwardly ; fore femora very stout, and carrying beneath a row of 

 six or seven stout setae, placed rather far apart ; rostrum stout, extending 

 to intermediate coxae. 



In being furnished with spines on the middle of the body, and also 

 with pale foliaceous margins at the same parts, this larva is unique in 

 the genus Nahis, and what is still more remarkable, these organs and 

 markings entireh' disappear in the adult insect; no other British Nahis 

 has any spines at all, either as larva or as adult, nor has any other 

 species those distinct white markings which seem, as it were, to narrow it 

 at the waist. Here, then, is a whole set of apparatus, which is purely 

 temporary in character, and is destined to be entirely discarded when 

 the insect attains maturity ; the problem is, therefore, to find a valid 

 reason both for their presence at all, and on this species alone. Of course 

 these spines add somewhat to the ant-like appearance of the larva, but 

 that by itself does not bring us much nearer to an explanation, and Ave 

 need to find out what advantage it is to the 3^oung larva, if any, that it 

 should be myrmiciform ; we will recur to this question presently. 



The structure of the tarsi, on the other hand, is characteristic not 

 only of the whole genus in the larval form, but equally so of the 

 liediiviidae, Anthocoridae, and Saldidae. In the adult in all these, 

 the long terminal joint becomes divided nearly equally, making the tarsi, 

 -after the last moult, trimerous. The rostrum is characteristic of a pre- 

 daceous insect, not being enclosed between bucculae, but being strongly 

 •curved and meeting the body at the apex only ; thus it has complete 

 freedom of motion, and can be thrust forward to reach prey in front 

 oi it. 



A later instar, measuring not quite 4 mm. in length, is similar to 

 the above, but darker, and with the long hairs much stouter and the 

 antennae proportionately inore slender ; hind tibiae strongly fringed 

 inwardly ; white foliaceous expansions at base of abdomen broader and 

 more distinct. 



The last instar measures 6 mm. Head similar in shape to that of 

 adult, but eyes not quite so jDromineut, and still no ocelli, though there 

 are faint indications of the spots at which these will appear ; surface 

 between eyes distinctly shagreened, the other parts more faintly so. 

 Colour of foxe-parts deep chocolate-brown ; pronotum trapezoidal, very 



