20 Mammalia. 



lates ; and it sotnetimes forms part of the wall of the cranial 

 cavity : this last function of the squamosal is peculiarly Mam- 

 malian, but by no means constant in all members of the 

 class. The tympanic portion is attached to the petrous 

 either by suture or ligament, and is of various size and shape 

 (cf. V. vi. xi). The mastoid process is generally very slightly 

 developed. The Styloid process frequently exists as a sepa- 

 rate ossicle. The Facial bones are immovably connected with 

 each other (cf. Aves). The Malar bone is seldom wanting, 

 but varies in size and shape (cf. vi. xi. xiii) ; its frontal pro- 

 cesses seldom reach the frontal bone (cf. viii, 1 ; x, 2) and 

 very rarely (cf. i. ii, 1) is there an inner plate developed, 

 circumscribing the orbit and zygomatic groove. The Lachry- 

 mals are very rarely wanting, but vary in size (cf. vi, 4 ; viii, 

 1 ; x, 2 ; xv), being usually more developed than in Bimana, 

 and contributing more to form the inner wall of the orbit, 

 where they seem to occupy the place of the ethmoid. The 

 Nasal bones are generally double, and very long (cf. ii, 1 ; viii, 

 1 ; X, 2). The Intermaxillaries, which in Bimana are distinct 

 only in the earliest foetal periods (till the fourth month) occur 

 in all other Mammalia, and generally support incisor teeth 

 (cf. X, 2. &c.) : they frequently coalesce in old individuals 

 at the median line, and with the superior maxillary bones. 

 The Superior MaxiUaries are more elongated than in Man, 

 and have a broader nasal process. The Palate bones have, in 

 most Mammalia, a large horizontal piece, by which the pos- 

 terior part of the hard palate is formed (cf. iv.) ^Each of the 

 two Rami of the lower jaw, though developed from several 

 centres of ossification, consists in the adult of but one single 

 bone, which has generally an ascending process : and which 

 articulates directly with the squamosal element of the skull, 

 and not with the representative of the quadrate bone of the 

 lower Yertebrata, which in the Mammalia is appropriated as 

 malleus to the service of the organs of hearing : the articu- 



