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 papyracea] , 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 nasal bones are very narrow in the 

 quadrumanous mammals and unite in many species to form a single 

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

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

 turbinata mferiora) seem to be present in all mammals 1 . In the 

 ruminants they appear as two laminae proceeding from a horizontal 

 basal piece, of which one is rolled upwards, the other downwards, 

 and which are perforated 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 2 . The 

 lachrymal bones lie on the outer margin of the nasal process of ^the 

 superior maxillary bone. They are usually more powerfully deve- 

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

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

 ruminants and in some edentates (Dasypus, Myrmecophaga) they 

 are much developed on the surface of the face, since the nasal pro- 

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

 this facial portion has in many ruminants (as in the stags) a deep 

 groove in which sebaceous glands are lodged. The upper jaw is 

 formed principally by the two 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 



1 That the whales form no exception to this, as MECKEL supposed (System der 

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

 small ossicles are found at the anterior margin of the nasal apertures behind the inter- 

 maxillary bone (STANNIUS Lehrb. der vergl. Anat. s. 364) ; in Balcence also ESCHRICHT 

 has found parts corresponding to the conchce; Untersuchungen ueber die nordischen 

 Wallthiere, Leipzig, 1849, s - I2 5- 



2 Comp. HABWOOD System of Comp. Anat. and Physiol. Cambridge, 1796, 4to. 

 pp. 2024. 



