1916. | F. H. GRAVELY : Lignicolous Beetle-Larvae. I51 
Hectarthrum trigeminum, Newman.! 
(Pl. xxii, figs. 18-22.) 
Locality.—E. Himalayas: Kalimpong, ca. 2500 ft., Darjiling 
District (in decaying wood with all stages of 
Mecistocerus sp.). 
Several larvae and pupae, the former 4°0-15'6 mm. long, the 
latter g'0-12°0 mm., found together with adults. The pupae and 
adults clearly belong to one and the same species; a cast larval 
skin secured with one of the pupae establishes the identity of the 
latter with the larvae, while in the largest of these larvae the skin 
is wrinkled and the spines of the pupa are clearly visible beneath 
it dorsally and laterally. 
The larva is a white fleshy and almost hairless grub. Its ab- 
domen is somewhat barrel-shaped, being thickest at about the 
fourth segment. The thorax is conical, and slenderer than the ab- 
domen, tapering away to the base of the small semicircular head, 
which bears a few minute hairs on its dorsal surface. 
The form of the head is shown in figs. 18 and 21 (pl. xxii). 
Each antenna arises from a low lateral convexity just behind the 
mandible; it is unjointed but is biramous, a small pointed branch 
being situated immediately below a stouter and slightly longer 
rounded one (pl. xxii, fig. 20). The mandibles are small and con- 
cave; they do not appear suitable for grinding fragments of wood. 
Their outer surface is whitish near the base, but they are narrowly 
bordered and extensively tipped with dark brown. They are 
tridentate at the tip (pl. xxii, figs. Ig and 21), the middle one of the 
three teeth being much longer than the other two, of which the 
dorsal is much broader than the ventral ; there are no other teeth 
on the dorsal margin of the mandible, but the ventral terminal 
tooth is followed by another tooth of about the same shape and 
size, and this is followed by a strong convexity of the raised mar- 
gin (pl. xxii, fig. 19). The maxillae and labium (pl. xxii, fig. 22) are 
rudimentary likethe antennae. The blade and palp of the maxillae 
are imperfectly separated ; the former is broader but no longer 
than the latter, and each is tipped with a cluster of small spines. 
The labium is a bilobed structure, with a papilla mounted on each 
lobe, tipped with small spines and doubtless representing a palp. 
The legs are short, stout and conical; they have two well- 
marked white fleshy joints and a stout terminal claw; as seen from 
the outer side there appears to be a third joint at the base, but it 
is not clearly marked off from the body on the inner side. The 
second thoracic segment, and each abdominal segment except the 
ninth (anal), bears a pair of circular stigmata a little behind the 
anterior margin; but the last pair is much smaller than the others. 
The anal segment bears a pair of black forwardly curved hooks on 
the posterior margin of its dorsal surface. 
! | am indebted to M. A. Grouvelle for this identification. 
