1897.] The Origin of the Galapagos Islands. 869 
The general distribution of Pocillopora and the Trapeziide 
in the Indo-Pacific region, can only be explained by a former 
land connection of thisregion. Let us suppose for one moment 
that the Pacific Islands had been elevated gradually by vol- 
canic activity, how was it possible that Pocillopora and at the 
same time the Trapeziide reached all these islands? There 
were no corals or Trapeziide near these islands which were 
elevated from theogean. If we consider the Pacific Islands as 
the remains of a former Pacific continent, we have no difficulty 
whatever in explaining the general distribution of Pocillophora 
and the Trapeziide. Both are of recent origin (miocene) and 
demonstrate that the Pacific continent must have still existed 
just before this time. I have shown that the Galapagos Is- 
lands were separated from Central America during the miocene, 
and the geology of the Fiji Islands shows that the first sedi- 
mentary strata are also miocene. 
We may now examine the distribution of a family of Decap- 
ods, the Atyidæ, which is confined to the fresh-water." 
Geographical Distribution of the Decapod Family Atyidæ Kingsley. 
ATYIDZ. 
Hiphocaris v. Martens, 1872. 
1. Hiphocaris elongata (Guérin), 1857. 
Distribution: Fresh-waters of the Antilles; Cuba; Hayti; 
Dominica ; San Domingo. 
2. Hiphocaris compressa (de Haan), 1849. 
Distribution: Fresh-water of Australasia; Japan: Yoko- 
hama, Tokio; Island of Adenare, near Flores; Queensland : 
Burnett. 
Troglocaris Dormitzer, 1853. 
1. Troglocaris schmidti Dormitzer, 1853. 
Distribution: In the waters of the caves of Carniola; caves 
of Kumpole and Gurk (Dormitzer). 
3 Ortmann, Arnold E. A Study of the Systematic and Geographical Distribu- 
tion of the Decapod Family Atyide Kingsley. . Proc. Acad, Nat. Sci. Phila., 
1894, p. 397--416. 
