100 
PACIFIC SCIENCE, Vol. XV, January 1961 
. . . were to be seen in moist, shady places all 
over the island. A small miller was common dur- 
ing the night, and I am of the opinion that the 
skinks and geckos feed on it as well as on the 
small flies just mentioned. . . . 
The only spider that had established itself 
was the widely distributed web-spinning species, 
Epeira nautica. . . . Trees and grass showed little 
or no signs of insect pests. In fact, I found only 
one species of plant that had been molested by 
biting insects. Since these depredations were to 
be seen only in a very limited area, and as I was 
unable to secure the miscreant either by day or 
night, I concluded the species must have been 
a recent Japanese introduction that had not had 
time to thoroughly establish itself. No species 
of Coleoptera were secured [pp. 117-8}. 
No land shells were noted, and I believe there 
were none [p. 120}. 
Believing that a collection of any earthworms 
that might occur on the island would be of 
interest I requested Mr. Sedgwick and his as- 
sistants to keep a close lookout for them. Al- 
though they made a large number of excavations 
in various places while prosecuting their inves- 
tigations, they were unable to discover a single 
specimen. ... I am persuaded that worms of this 
class have not as yet found their way thither 
[p- 122}. 
Compare these citations with results obtained 
by me, and remember that both surveys were 
made approximately in the same season and 
during the same interval (cf. Appendix, 1902). 
It may be assumed that, in all probability, many 
species now inhabiting the island were estab- 
lished there after 1902. 
Only Neoscona theisi (Walckenaer) (= Ep- 
eira nautica Bryan nec Koch) and, seemingly, 
some domestic dipterans are the inhabitants col- 
lected in both surveys. It is not certain whether 
Bryan’s "red, small ant” corresponds to any of 
four ant species collected by me or not. But 
it surely differs from Lasius niger, the com- 
monest ant in 1952. 
Consequently, judging from their conspicu- 
ousness and present abundance, the following 
species may safely be regarded as immigrants 
since 1902: 
Plexippus paykulli Prodenia litura 
Heteropoda venatoria Herse convolvuli 
Periplaneta americana Sceliphron caementarium 
P. australasiae 
Landreva clara 
Locusta migratoria 
? Allolobophora sp. 
A land snail 
Lasius niger 
Calandra oryzae 
Cylas formicarium 
Tribolium castaneum 
Eobia chinensis 
Although with less certainty, the following 
species are also assumed to be relatively recent 
immigrants: 
Armadillo sp. 
Ctenolepisma villosa 
Euborella annulipes 
Anisolabis martima 
Aiolopus tamulus 
Oligotoma saundersi 
It is uncertain whether or not a "red moth” 
mentioned by Yoshida corresponds to Utetheisa. 
But, from Bryan’s notes, it is highly probable 
that the number of individuals was very small, 
even if this species was present in 1902. 
Matsubara wrote me only about the skink, 
gecko, land crab, flies, and cricket as being the 
impressive animals during his wartime service. 
From these accounts, we can assume that Land- 
reva was established before 1943. On the other 
hand, Locusta, Eiobia, and Periplaneta must have 
arrived after World War II, for these animals, 
if they occurred, certainly would have attracted 
the attention even of persons not biologically 
observant, either by their conspicuousness (as 
in Locusta) or by their sanitary importance. 
Needless to repeat, the species now most abun- 
dant are, in general, the relatively recent im- 
migrants. 
Thus, most members of the land biota of 
Marcus are immigrants since 1902. Consider- 
ing the extremely isolated location of the is- 
land, it must be obvious that most of these 
species gained their chances to arrive on the 
island and to establish themselves there only 
through direct and indirect human interference 
at the island. My conclusion, therefore, is that 
the present land biota is, in its origin, largely 
an outcome of human activities directed upon 
the island. 
CONCLUDING REMARKS AND 
GENERAL CONSIDERATIONS 
In connection with the zoogeography of Pa- 
cific islands, Gressitt (1956) gave an appro- 
priate summary on the nature of land fauna in 
