366 MR. R. I, POCOCK ON THE fApr. 21, 
Part lV. 
DisTRIBUTION OF SOME OF THE FAMILIES OF ARACHNOMORPHE 
THAT WERE REPRESENTED IN THE OLIGOCENE PERIOD. 
The only fossil Spiders, with one or two exceptions, of which 
the generic determination may be trusted, are those that have 
been found in the amber-beds of Oligocene age. Those that have 
been referred to genera not now known to exist have no special 
importance from a geographical standpoint; but of those that 
have been assigned to existing genera, the following may be taken 
as a fairly complete list :—Segestria and Dysdera (Dysderide) ; 
Eresus (Eireside) ; Amaurobius (Dictynide); Aranea, Zilla, Tetra- 
gnatha, and Nephila (Argiopide) ; Archea (Archeidee) ; Tegenaria 
and Agelena (Agelenide); Drassus (Drasside); Clubtona, Any- 
phena, and Sparassus (Clubionide) ; Thomisus and Philodromus 
(Thomisidee). 
Although since the Oligocene these Spiders have had the same 
time for dispersal, they nevertheless differ greatly in their distri- 
bution. Dysdera, for example, is apparently indigenous only in the 
Mediterranean and central portions of Europe and Asia’; Hresws is 
found in South and Central Europe, Central Asia, China, and Africa 
to the north and south of the Sahara; Amaurobius all over the 
world with the exception of India, tropical Africa, and Madagascar ; 
Aranea and Tetragnatha are cosmopolitan; Wephila is mainly 
restricted to the tropics and the Southern hemisphere, though in 
Eastern Asia it extends as far north as Japan, and in North 
America enters the Southern States of the Union; Archea is 
known only from Madagascar; Tegenaria is indigenous apparently 
only in Europe and North America; <Agelena in Hurope, 
South Africa, India, and Burma; Anyphena in North, Central, 
and South America (Andes), Japan, India (in the mountains), 
and Central Europe. 
The Hersiliidee were represented in the Oligocene of Hurope. 
The four existing genera are distributed as follows :—AHersiha 
ranges from the southern area of the Mediterranean as far as 
Malaysia in the Oriental Region, and over Africa and Madagascar. 
Tts very near ally Murricia is confined to India; Herszliola is 
known only from the Mediterranean Region and 8. Africa. Zama, 
next to Hersiliola the most primitive of all the genera, occurs in 
the Mediterranean, Oriental, Australian, and Neotropical Regions. 
The distribution of the group offers no difficulties to the hypo- 
thesis of a southern migration from EKurope. The absence of the 
genus Zama from North and Central America strongly suggests its 
existence in South America to be attributable to migration from 
Australia. 
Two genera of Hresidz have been recorded from the European 
1 Specimens that have been recorded from the Southern hemisphere are mostly, 
probably in all cases, referable to imported European species. 
