No. 403.] REVIEWS OF RECENT LITERATURE. 597 
the lack of certain groups of animals is apparently due to the fact 
that they did not exist at all at the time when there was a connection 
of these parts with others. 
But we need further investigations on this subject, and it is not 
advisable to express at present a definite opinion on this topic. 
Hedley’s paper gives one solution of the problem, and, indeed, his 
arguments are very important, and his theory may finally prove to be 
correct, at least to be the most probable. ALO 
The Distribution of the Opilionidæ. r. J. C. C. Loman’ has 
published a synopsis of the facts known about the distribution of the 
Opilionidz, illustrated by four maps. It is hardly necessary to dis- 
cuss the paper in detail, as the author intended simply to give the 
facts, without giving an explanation of them. We should like, how- 
ever, to call attention to certain features of the distribution of these 
animals which seem to furnish additional evidence in favor of von 
Ihering's theories. 
It will be remembered that, according to von Ihering, South 
America is no zoógeographical unit, but consists of two separate 
centers of origin; the one is situated in its southern part and was 
connected at a certain time with the antarctic continent; this is 
called “ Archiplata” ; the other one comprises the northern parts of 
the present South America, and was connected, in Mesozoic times, 
with West Africa. This Mesozoic continental mass has been called 
by von Ihering by the name of * Archhelenis." 
Now, according to Loman's map (Pl. XI, Fig. 2), the distribution 
of the Opilionid family, Gonyleptoidz (expressed in green dots), is in 
South America and the West Indies on the one side, and in West 
Africa on the other, and it would seem impossible to explain it 
in any other way than by accepting von Ihering's Archhelenis 
eory. 
The relations of the southern parts of the present continents to 
the antarctic continent supposed to have existed formerly are expressed 
in the distribution of another family of Opilionids, the Triaenony- 
choide. As Loman's map (Pl. XI, Fig. 4) indicates (by red dots), 
this family has been found in South Africa, Madagascar, South 
Australia, the Fiji, and in Chili. This distribution corresponds 
closely to that of other antarctic animals. X E 
! Ueber die geographische Verbreitung der Opilioniden, 'Zoo/. Jahré., Abt. f. 
Syst., Bd. xiii (1 900). 
