FOSSIL VARANIDAE AND MEGALANIDAE. 
425 
bable. And if Isay : as far as Austral-A s i a, this is because the fossils 
obtained from there are all of the more recent Pliocene or Pleis¬ 
tocene period; so that according to our knowledge, we have no reason 
to believe the Varanidae originated from Asia. I have, it is true, with re¬ 
gard to the geographical distribution of Varanus marathonensis, men¬ 
tioned in what way it seemed possible, though in a purely h y p o- 
I h e t i c a 1 manner, from the palæogeographical point 
of view and considering the connexion of the continents, to s u p p o s e 
an Asiatic origin of Varanidae. I must however repeat that this is a mere 
Fig. 23. Aspect of the World at the Diluvial Period. — The limits of Continents rep¬ 
resent those existing at the beginning of the Diluvium. — Continental Inlandice ; 
punctuated red. Maritime Inlandice : uniform red.*: Centres of Glaciation. (After Koken 
[in Arldt, op. eit., Karte 22] drawn by Miss! F. Lángh & the authoi). 
supposition lacking every positive basis and which, 
on my part, I cannot but consider as improbable. The reasons which 
lead me to this conclusion are that an Asiatic origin could in this case only 
be surmized in one of the two following ways : 
1 Either in general, for the whole family Varanidae, which 
would oblige us to, absolutely pretermitting every positive 
fact, by sheer fancy, admit the possibility of Varanidae 
existing in the more ancient strata of Asia, although not .having as yet 
been met with. Such unfounded opinions would however only unnecessarily 
burden literature, and have no place in science. The above hypothesis is 
just as improbable from a biological point of view, for, as 
