INSECTIVORA 611 
foramen. Certain forms, such as Talpa and Guleopithecus, are unique 
among mammals in having ossified intercentra in the dorso-lumbar 
region of the vertebral column. 
Representatives of this order are found throughout the temperate 
and tropical parts of both hemispheres ; 
(except South America and Australia), 
and exhibit much variety both in 
organisation and in habits. With the 
exception of the Tupaiide, all are noc- 
turnal; the greater number are cursorial, 
but some (Talpa, Chrysochloris, Oryzorictes) 
are fossorial ; some (Potamogule, Necto- 
gale, Myogale) are natatorial, and a few 
(Tupatide) arboreal; while the species 
of the aberrant genus Guleopithecus glide 
through the air like the Flying Squirrels. 
To the great majority the term insecti- 
vorous is strictly applicable, Galeopithecus 
alone being phytophagous ; while Pota- 
mogale is said to feed on fish, and the 
different species of Moles live chiefly on 
worms. The general organisation of the 
Insectivora indicates a very low type, 
and were it not for the specialised , Fio- 28. Upper surface of the 
character of their placentation and the Geel, Paes sta, oa. 
tendency to lose the differentiated char- 
acters of the anterior teeth they might be regarded as closely 
allied to the ancestral type of many of the heterodont mammals. 
The strongly marked distinction of the canines from the incisors 
and anterior premolars in the Mesozoic and most of the Tertiary 
mammals (excepting some of the Ungulates) points, however, very 
decidedly to the conclusion that the want of definition between 
these teeth in many of the modern Insectivora is an acquired 
feature. Fossil forms apparently indicate a relationship on the 
one hand with the Creodont Carnivora, and on the other with 
the Lemuroid Primates ; indeed it is in some instances impossible 
to say whether'extinct genera are really Insectivores or Lemuroids. 
In most Insectivora the cranial cavity is of small relative size, 
and in none is the brain-case elevated to any considerable extent 
above the facial line. The facial part of the skull is generally 
much produced, and the premaxillary and nasal bones are well 
developed. The zygomatic arch is usually slender or deficient, the 
latter being the case in most of the species; and postorbital pro- 
cesses of the frontals are found only in the Galcopithecide, Tupaiide, 
and Macroscelidide. The number of dorsal vertebre varies from 13 
in Talpa to 19 in Centetes,; that of the lumbar from 3 in Chryso- 
