78 
PACIFIC SCIENCE, VoL XIV, January I960 
at Robbins Farm.” Probably the land rails sur- 
vived the rat invasion but, not being very num- 
erous, escaped observation. 
REPTILIA 
The fauna of reptilia is extremely poor. Corrie 
( 1878 ) stated wrongly that neither snakes nor 
lizards are known on the island; snakes are cer- 
tainly unknown, but three species of Lacertilia 
are present. 
There are two species of Geckonidae: Phyl- 
lodactylus guentheri Boulanger and Gehyra 
oceanica Grey. The first is also known to exist 
both on Norfolk Island and in northwest Aus- 
tralia, the second appears to be generally dis- 
tributed throughout the South Pacific islands. 
The distribution of geckos is usually connected 
with the transportation of various tropical fruits 
in bunches, in which they often hide. More 
interesting from the zoogeographical point of 
view is the presence of the third species, Lygo- 
soma lichenigerum O. Shaun. (Scincidae). The 
three species are also distributed on Rabbit 
(Goat) Island and the Admiralty Islets. They 
may be sought on dry stony ground, under 
stones, amongst dry leaves, and at the feet of 
low scrubby trees. 
Of water chelonians there is no trace. Turtles 
are, however, known to frequent occasionally the 
shores of the island. In the early decades of the 
last century they were very numerous. 
AMPHIBIA 
Frogs, etc., are quite absent. The absence of 
amphibians may be connected with the absence 
of permanent fresh-water pools on the island. 
The Evertebrata will be discussed in some 
detail later. 
FRESH-WATER FAUNA 
The fresh-water fauna of the island is very 
poor, but interesting. The poverty of this fauna 
can be easily explained by the absence of large 
permanent streams or water pools. In each large 
valley there are streams but they are not truly 
permanent. One of the bigger streams is situated 
at northern part of the settlement, but its 
estuary is usually filled with salt water which 
enters during high tide and extends rather far 
inland. There are also some isolated lagoons, but 
their fauna was not studied regularly. 
However, there are some species with ex- 
tremely peculiar distributions. For example, 
under stones in the several streams, anywhere 
from sea level, as In the Big Creek, to the moun- 
tain tops, there is living a tiny fresh-water crab, 
Hymenosoma lacustris. This species is the only 
fresh-water representative of a common marine 
genus. It was first recognised in New Zealand, 
later it was found in landlocked lakes in Vic- 
toria, Australia, and afterwards at Lord Howe 
and Norfolk islands. Its permanent associate is 
a fresh-water prawn, a Paratya (Xiphocaris) 
species. 
How is it that these species appear in fresh 
water in such widely separated localities? It 
might be supposed that they spend some of their 
earlier stages in the sea and that later some in- 
dividuals have drifted from one locality to an- 
other. However, this suggestion is discounted by 
the fact that they occur in landlocked lakes, and 
on Lord Howe Island on the top of Mt. Gower, 
to which access from the sea is impossible be- 
cause the streams from the top disappear before 
they reach sea level. 
We could suggest that the crab and the prawn 
are survivors of an ancient fauna which passed 
from one place to another by means of old land 
connections, long since disappeared. But this ex- 
planation is also unsatisfactory, because we must 
suppose a land mass including Victoria, Norfolk 
Island, Lord Howe Island, and New Zealand and 
the commonest animals and plants of all the 
above-mentioned areas are not preserved on 
Lord Howe Island. 
Again, we could imagine also that the eggs 
were transported upon the feet of wading birds, 
but if so, why do these crabs and prawns not 
live in all the lakes of Australia, but only in 
some of them in Victoria? 
It is necessary to add that in addition to the 
crabs and prawns there are tiny eels (Anguilla) . 
Their occurrence on the summit is more easily 
explained, for young eels can migrate for con- 
siderable distances along streams and over moist 
surfaces. Although their occurrence on the sum- 
mit can be accepted it is not possible to imagine 
where they would find conditions suitable for 
development to maturity. 
Thus, the distribution of these animals is 
mysterious. R. Etheridge, Jr. (1889: 32) also 
