Genera of the CossonidcB. 515 
the island of Ascension,* the Malayan and Japanese archi- 
pelagos. New Zealand, Chili, and Brazil.f 
14. Sericotrogus {nov. gen.). — I am indebted to Dr. 
Sharp for the very curious little Pentarthrid for which the 
present genus is established ; and he appears to have ob- 
tained it from Mr. Lawson, of Scarborough, by whom it 
was received fi-om Auckland in NeAv Zealand. Its dis- 
tinct scutellum and largely-developed eyes place it very 
near to Pentarthrum proper; nevertheless in its smaller 
bulk, and slenderer aud more fusiform outline (the elytra, 
as in Amaurorrliinus, being narrowed anteriorly), and in 
its somewhat brassy surface, which is sparingly clothed 
Avith a coarse, silken, decumbent Eeneo-cinereous pubescence, 
as well as in its less elongated metasternum (which is like- 
wise more on the Amaurorrhinus type), and the widely 
bilobed third joint of its feet, it altogether recedes from the 
members of that group. Its rostrum, too, is a trifle longer, 
thinner, and more curved than in the majority of the Pen- 
tarthra, and has the antennae implanted into it rather more 
conspicuously before the middle ; the latter are a little less 
thickened ; its head is more exserted : its prothorax (which 
is slightly concave beneath) is convexer, more regularly 
rounded at the sides (it being neither subtriangular nor 
subcylindrical), and is nearly free from an anterior con- 
striction : and its elytra have apparently no tendency to 
be separately rounded-off", and subreciuwed, at their ex- 
treme apex. 
15. Stenotrupis (nov.gen.). — The exceedingly narrow. 
common ; or than placing Hexarthrum amongst the RhyncoU, because 
the articulations of the same organ were incorrectly counted ! But if col- 
lectors will not take the trouble to expand their specimens so that the parts 
may be distinctly seen, how can we wonder at the inevitable results ? Still, 
one would at least have supposed that before enunciating a new form, the 
microscope would, as a matter of necessity, have been appealed to. 
* The presence of my P. cylindricvm in the island of Ascension appears 
to have been (as indeed I always anticipated) merely accidental ; for an 
example is now before me which was captured by Mr. Fry in Brazil, and 
another which was taken by Mr. Wallace in Gilolo of the Malayan archi- 
pelago. In all probability therefore it is a species which, like certain 
others, is liable to follow in the wake of civilization. 
f The little insect from St. Helena which I described two years ago as 
an aberrant Pentarthrvm, under the name of P. suhccecum, proves on a 
closer examination to be no Pentarthrrtm at all, but more intimately re- 
lated to Amauroi'rhinns (or Mesuxenvs). It is, however, distinct from 
even the latter, and forms the type of my genus Pseudomesoxeniis, — 
enunciated below. 
