INSECTIVORA 



6n 



foramen. Certain forms, such as Talpa and Galeopithecus, 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 Tiqxdidu:, all are noc- 

 turnal ; the greater number are cursorial, 

 but some (Talpa, ChrysocMoris, Oryzorictes) 

 are fossorial ; some {Potamogale, Necto- 

 gale, Myogale) are natatorial, and a few 

 (Tupaiidce) arboreal; while the species 

 of the aberrant genus Galeopithecus glide 

 through the air like the Flying Squirrels. 

 To the great majority the term insecti- 

 vorous is strictly applicable, Galeopithecus 

 alone being phytophagous ; while Poia- 

 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 Fig. 28i.- Upper surface of the 



. . . . . • i j.i brain of Tupaia ferruginea. (From 



character of their placentation and the G arrod, Proc. zooi. soc. 1879, p. 304.) 

 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 Lemuroid s. 

 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 Galeopithecidw, Tupaiidce, 

 and Macroscdididce. The number of dorsal vertebra? varies from 1 3 

 in Talpa to 19 in Cenktes; that of the lumbar from 3 in Chryso- 



