THE INSECTS OF ST. HELENA 
389 
ncte he recorded two scorpions (Lychas maculatus and L. 
americanus). These have since been shown to be both forms 
of Isometrus maculatus, a cosmopolitan species of the tropical 
and sub-tropical zone. In Europe it occurs only in the south 
of Spain.* 
The total number of land-shells indigenous to St. Helena 
is estimated by Mr. Smith as amounting to twenty-seven 
species. With regard to their origin, he likewise rejects the 
theory of a possible land connection of the island with either 
Africa or South America, or, indeed, any other land surface. 
All the same, he points out that there is a greater resemblance 
between the molluscan fauna of St. Helena and South 
America than was recognised by previous observers. It is 
especially a species resembling the exclusively Brazilian 
genus Tomigerus that seemed to Mr. Smith to point to South 
America as the likely source of some of the indigenous species. 
He does not feel tempted to probe further into this mystery, 
for he exclaims, “ How they were transmitted is a hopeless 
problem to solve, and although drift-wood, carried by oceanic 
currents, is doubtless answerable for a good deal in the way 
of distribution the subject must apparently ever remain one 
of mere speculation.” Nevertheless Dr. Ivobelt f regards it as 
highly probable that this molluscan fauna is the last remnant 
of that of an ancient Mesozoic continent. 
About half of the species of the snails of St. Helena are 
now extinct and occur only in a sub-fossil condition. Hyalinia 
cellaria, H. alliaria and a few others, along with Amalia 
(Milax) gagates are supposed to have been introduced with 
plants. It is quite possible that some of them were brought 
to St. Helena in that manner, still it is very remarkable that 
the only slug thus conveyed should be one of our rarest, 
British species, and the one which has the widest range of all 
slugs. It occurs in California, New Zealand, and other remote 
localities, while none of our common Arions, Agriolimaces 
or Limaces have found their way to the island. I am fully 
convinced that Amalia gagates is one of the most ancient of 
our European terrestrial species, as I explained in a previous 
* Pickard-Cambridge, 0., “ Spiders and Scorpions of St. Helena,” p. 544, 
f Kobelt, W., “ Zoogeographische Stellung von St. Helena,” p. 201. 
