INSECTIVORA. 637 



mammalian number of teeth, i ^ c \ p ^ m i} (e.g., Talpa, 

 Myogale), but there are usually reductions. The incisors are 

 primitively conical, and are occasionally enlarged in a rodent- 

 like manner. The posterior incisor sometimes has two roots 

 {Erinaceus, Galeopithecus). The canines are not usually strongly 

 developed and may have two roots {Erinaceus, Talpa, Galeo- 

 pithecus). The premolars are usually sharp and pointed, but 

 the last may be like the molars. The upper molars are three- 

 or four-cusped, the cusps being isolated or connected by ridges. 

 The last molar is frequently smaller than the others. The 

 lower molars have three cusps in front and a talon which is often 

 two-cusped behind. There is a milk dentition, which however 

 is frequently absorbed in utero. 



The skull is elongated and depressed, and has a small cranial 

 cavity. The orbit is not closed by bone except in the Tupaii- 

 dae. The palate is very generally incompletely ossified, and 

 the angle of the mandible may be inflected as in marsupials ; 

 and as in that order the alisphenoid contributes to the anterior 

 wall of the tympanic cavity. The tympanic bulla is rarely 

 completely ossified and frequently falls off in the dry skull. 

 The mastoid process is often marked and sometimes joins the 

 postglenoid process of the squamosal below the external auditory 

 meatus. The jugal is often weak and sometimes absent, in 

 which case the zygomatic arch is incomplete. 



The vertebral column presents considerable variations, both 

 in number and character of vertebrae, even in different species of 

 the same genus. The lumbar region often presents intercentra. 



The scapula has a well developed spine with an acromion and 

 often a metacromion. A clavicle is present in all except Pota- 

 mogale. The humerus usually has an entepicondylar foramen, 

 and the radius and ulna are generally separate. The scaphoid 

 and lunar are fused in some genera (e.g. Galeopithecus, Tupaia, 

 Erinaceus, etc.), and there is usually a centrale in the carpus. 

 The manus has typically five digits, but the pollex may be 

 aborted. The femur often has a third trochanter. The fibula 

 is usually united with the tibia, but in a few genera it is free. 

 The digits of the pes are five, but the hallux may be absent. 

 The pelvis presents considerable variations ; the pubic sym- 

 physis being long, short or absent (e.g. Talpa). 



The brain is small. The cerebrum never projects back over 



