288 RHYNCHOPHORA. 
with an irregular knob-like process, bent inwards and separated from its fellow by an emargination more 
than twice as broad as deep; surface longitudinally convex, punctured in irregular rows, obliquely retuse 
and shallowly excavate for the hinder third, the excavation concave, shining, closely punctured, its margins 
forming a broad oval, and subacutely elevated, with a short pointed tooth above cn each side of the suture, 
which is thickened about the middle and callous below before the apical nodosity. Underside fuscous ; 
prosternum not prominent. Anterior tibie linear, straight, with close fine serration. 
Hab. Guatemata, Mirandilla (Champion). 
One example. A more robust insect than 7. ovicollis, with less cylindrical elytra, 
and distinguishable by the somewhat distant knobbed processes at their apex. 
AMPHICRANUS. 
Amphicranus, Erichson, Wiegm. Arch. 1836, i. p. 63; Hichhoff, Rat. Tom. p. 462. 
Piezorhopalus, Guérin, Rev. Zool. 1838, p. 107. 
In this genus, which contains some of the most highly specialised forms among the 
Tomicini, the elytra are excavate behind, or at least retuse, and either explanate at 
the apex (A. retusus, A. brevipennis), or more commonly produced into two parallel 
gouge-like processes, separated by a narrow interval and concave on the inner face. 
In the larger and more typical species the head is concealed, the prothorax being 
vertically declivous towards the anterior opening, which is often trisinuate; in the 
smaller forms the front of the prothorax is diverse in structure, being either vertically 
declivous (A. hybridus), obliquely declivous (A. collaris), produced beyond the head 
and rounded at the tip (A. propugnatus), or prolonged into an acute peak (A. fastigatus). 
The antecoxal portion of the prosternum is variable: shorter in the larger species, it 
is very long in the smaller slender forms (A. bipunctatus, A. filiformis, &c.); its hind 
margin is quite transverse, so that the anterior coxe appear to project from a common 
cotyloid cavity. Unfortunately the differences in its length are not easily to be employed 
for subdividing the genus. The funiculus is three-jointed; but in the types of A. fili- 
formis and A. hybridus the third joint is not distinguishable. The club is oval, 
moderate or large; in the larger species it is closely pubescent, with some longer hairs 
on the inner face, and with the sutures strongly curved or angulate, at least on the 
outer face, so that the second joint is chevron-shaped; in the smaller species the 
sutures are subtransverse, or obtusely curved on both faces, and the surface is scantily 
hairy. 
In A. hybridus the club is fringed with long hairs, as in a female Pterocyclon, and 
the species may be regarded as an osculant form between the two genera. It and 
A. filiformis, which also resembles Pterocyclon in the two-jointed funiculus, are 
separable from that genus by the long antecoxal portion of the prosternum and the 
structure of the elytra. 
Any sexual differences which may exist in the species of Amphicranus are unknown 
to me; Eichhoff, without any ascertainable reason, has in A. retusus indicated as 
