570 CLASS XVII. 



mammals, considerably smaller than in man when the eyes are 

 near together, as in the monkeys. The smooth lateral plate, which 

 in man and the monkeys contributes to form the inner wall of the 

 orbit {lamina pajjyracea) , is wanting in almost all the rest of the 

 mammals. The nasal bones are large in the carnivores, in the horse, 

 the swine, and especially in the rhinoceros and the rodents. In 

 the rhinoceros they support the horn by which this genus of animals 

 is distinguished; in the two-horned species the posterior horn is set 

 upon the frontal bone. The niasal bones are very narrow in the 

 quadrumanous mammals and unite in many species to form a single 

 bone; this, however, is often tlie case in other mammals where they 

 are larger. The inferior turbinate bones [conchce inferiores, ossa 

 turbinata inferiord) seem to be present in all mammals ^ In the 

 ruminants they appear as two laminae proceeding from a horizontal 

 basal piece, of whicl' one is rolled upwards, the other downwards, 

 and which are perforai^.d by many apertures. In the carnivores (as 

 may be seen particularly in Phoca, Lutra, &c.), as well as in many 

 rodents [Lepus, Sciurus, Castor, &c.) these turbinate bones consist 

 of numerous hollow tubes which divide into fine branches^. The 

 lachrymal bones lie on the ou 3r margin of the nasal process of^tlie 

 superior maxillary bone. The r are usually more powerfully deve- 

 loped tlian in man, and contribute more to form the inner wall of 

 the orbit, wliere they occupy the place of the ethmoid. In the 

 ruminants and in some edent? 'es [Dasypus, Myrmecopliarjo) they 

 are much developed on the sur :e of the face, since the nasal pro- 

 cess of the superior maxillary lones does not mount to the orbit; 

 this facial portion has in ma^ ' ruminants (as in the stags) a deep 

 groove in which sebaceous gl ads are lodged. The upper jaw is 

 formed principally by the tw ) superior maxillary bones and the 

 two intermaxillaries. These intermaxillary bones differ from the 

 single intermaxillary of birds (see above, p. 334) by the absence of 



^ That the whales form no exception to this, as Meckel supposed {System cler 

 vergl.Anat. ii. 2, s. 553), has been manifested by later investigations ; in the dolphins two 

 small ossicles are found at the a'- uerior margin of the nasal apertures behind the inter- 

 maxillary bone (Stannius ^ Jirh. der vergl. Anat. s. 364); in Balwnce also Eschricht 

 has found nn'-^- .^nesponding to the conchce; Untersucliungen ueher die nordischcn 

 Wallf^'.ie, Leipzig, 1849, s- ''^S- 



^ Comp. Hakwood System of Comp. Anat. and Physiol. Cambridge, 1796, 4to. 

 pp. 20 — 24. 



