474 
ME. H. N. EIDLEY ON THE 
very abundant and conspicuous G-ecko with the AmpTiisboena, 
which is often called the snake with two heads, or may have been 
suggested by finding an accidentally fork-tailed lizard, of which 
an example was obtained by our expedition. The “ serpents ” 
were doubtless the Amphisbcena. The large rats are much less 
easy to explain ; at present the only rats occurring on the island 
are Mus rattus , the common introduced black rat. It is impos- 
sible that the animals seen by Tespucci could have been this 
species, which could not at that time have been introduced. 
It is possible that there was formerly an indigenous rat-like 
mammal, which became exterminated by the black rat. We 
could find no tradition even of this big rat, and I fear it is quite 
extinct. The only hope of recovering its remains lies in an 
examination of the guano deposits of Eat Island, where its 
bones might be preserved. 
The number of insects belonging to the orders which are 
well known as plant-fertilizers is surprisingly limited. A few 
small species of moths haunted at night the bushes of Scoparia 
clulcis , Cassias, &c. on the open spaces. A single species of 
butterfly was very abundant on Eat Island and the main island, 
but we never saw it visiting flowers. 
The most important fertilizer was a small endemic hornet 
belonging to the genus Polistes , which gathered honey from the 
Leguminosse and Cucurbitacese ; and three small black species of 
Halictus were caught in the flowers of the melons, Momordica 
charantia , Oxalis Noronhce, and the mustard. The last plant 
was also haunted by Temnoceras vesiculosus, a pollen-eating 
Syrphid. The only other insects which could also be considered 
as possible fertilizers were Tacliytes inconspicuus, n. sp., and 
Monedula signata, two sand-wasps, Pompilus nesophila , n. sp. 
(Hymenoptera), and Psilopus metallifer (a Dipteron), but none 
of these were seen at or near flowers. A small black beetle also 
was found in the flowers of an Acacia in the Governor’s garden. 
Though the number of species of insects was not large, 
the individuals, especially of the Polistes and Halicti, were very 
numerous, but at the same time they seemed out of all propor- 
tion to the immense number of flowers to be fertilized. It is 
very probable, however, that the majority of the Leguminosse 
and some of the other plants were self-fertilized. 
The lake on the main island contained a species of Nitella and 
an alga, an aquatic beetle and an Hemipteron, a new species of 
