CHAP. XVII.] 
MAMMALIA. 
179 
discovered, which are believed to belong to this snb-order : but 
they form two distinct families, — Lemuravidae and Limnotheridse. 
Other remains from the Miocene are believed to be intermediate 
between these and the Cebidse, — a most interesting and suggestive 
affinity, if well founded. For the genera of these American 
Lemuroidea, see vol. i., p. 133. 
General Remarks on the Distribution of Primates. 
The most striking fact presented by this order, from our present 
point of view, is the strict limitation of well-marked families to 
definite areas. The Cebidae and Hapalidee would alone serve - 
to mark out tropical America as the nucleus of one of the great 
zoological divisions of the earth. In the Eastern Hemisphere, 
the corresponding fact is the entire absence of the order from 
the Australian region, with the exception of one or two outlying- 
forms, which have evidently transgressed the normal limits of 
their group. The separation of the Ethiopian and Oriental 
regions is, in this order, mainly indicated by the distribution of 
the genera, no one of which is common to the two regions. The 
two highest families, the Simiidse and the Semnopithecidae, are 
pretty equally distributed about two equatorial foci, one situated 
in West Africa, the other in the Malay archipelago, — in Borneo 
or the Peninsula of Malacca ; — while the third family, Oyno- 
pithecidae, ranges over the whole of both regions, and somewhat 
overpasses their limits. The Lemuroid group, on the other 
hand, offers us one of the most singular phenomena in geo- 
graphical distribution. It consists of three families, the species 
of which are grouped into six sub-families and 13 genera. One 
of these families and two of the sub-families, comprising 7 
genera, and no less than 30 out of the total of 50 species, are 
confined to the one island of Madagascar. Of the remainder, 
3 genera, comprising 15 species, are spread over tropical Africa; 
while three other genera with 5 species, inhabit certain restricted 
portions of India and the Malay islands. These curious facts 
point unmistakably to the former existence of a large tract of 
land in what is now the Indian Ocean, connecting Madagascar on 
the one hand with Ceylon, and with the Malay countries on the 
N 2 
