160 Proceedings of the Royal Physical Society. 
machetes, and set them to cut up the decayed trees. These heavy swords 
with long chopper-like blades, with square tips, a thick back and sharp 
edge to the front, can do wonderful work in the hands of a black man 
expert in woodcraft. 
After long search and breaking up of many trees, I found no specimens 
of Dynastes hercules, Linn., but many specimens of Passalus wnicornis, Serv. 
The name given to this insect by the natives is the Vo-Vo, and I was 
unable to obtain any information as to its scientific name, even after my 
return to this country. At last the Rev. James Waterston, now engaged 
in the British Museum (Natural History), kindly offered his assistance. 
He enlisted the aid of Mr C. J. Gahan of the British Museum, who 
identified it as Passalus wnicornis, Serv. Since then I have seen Mr 
Gahan, and he obliged by letting me view the collection under his care. 
I found that a specimen, in addition to the one given him by the Rev. 
Mr Waterston, already was in the British Museum, from Dominica, and also 
that the only other island of the Antilles from which specimens had been 
obtained was St Lucia. From the mainland of the north of the South 
American Continent were many specimens, especially from Ecuador and 
Colombia. 
It therefore seems probable that this beetle has a distribution some- 
what similar to that of its larger congener Dynastes hercules, Linn. The 
locality from which both beetles seem to have emanated, and at which 
they have still their strongest hold, is the mainland of South America, 
and it is an interesting problem that might at some future time be worth 
considering, as to how these insects and some other members of the 
South American fauna reached such a distant island as Dominica, without 
appearing on adjacent islands such as Guadaloupe or Martinique. 
Passalus unicornis, Sery., is furnished with powerful apparatus by which 
it can cut its way into timber. While I have only seen it working in 
decayed wood, it may possibly be very destructive to living vegetation. 
This beetle has a prominent single horn on the upper part of its head, 
from which it derives its name. 
The mites found upon Passalus wnicornis, Sery., are possibly new to 
science. Mr Stanley Hirst of the Natural History Department of the 
British Museum, South Kensington, writes me, 21st February 1914 :— 
“The mites which you found on the beetle Passalus wnicornis, Serv., 
belong to the genus Huzercon, but I cannot find out the name of the 
species, probably it has never been described.” 
(Issued separately, 27th June 1914.) 
