ii8 ELEMENTARY ANATOMY. [LESS. 



Often it is of great size, as in the Hare, Ant-eaters, and 

 Armadillos, or, as in the Deer, not only largely developed, both 

 in the orbit and on the cheek, but also presenting a peculiar 

 fossa destined to receive and shelter a special glandular 

 structure. 



This bone may join the malar, as in the Squirrel and the 

 Hog. Its junction with an os planum is a very exceptional 

 condition, though found in Apes as in man. 



It may join the palatine bone in the orbit, as e.g. in the 

 Rhinoceros. 



It may even complete the sub-orbital foramen superiorly, 

 as in Dolichotis. 



The lachrymal may develop a small process, as in the 

 Hare, or even a large osseous bulla, as in the Hippopotamus 

 and most Ruminants, notably in the Giraffe. 



29. The PALATINE bones of man are important and con- 

 stant elements of the vertebrate skull, being not only repre- 

 sented by ossified tracts in every osseous cranium, but being 

 also clearly represented by cartilage in skulls which never 

 become divided into separate bony elements. 



The condition, however, which each palatine presents in 

 man is a very exceptional one when we compare it with that 

 prevailing in Vertebrates generally, and its form and propor- 

 tions are exceptional even amongst Mammals, its vertical 

 extent in him so greatly exceeding its antero-posterior dimen- 

 sion. Already, in Apes, its length is greater in proportion to 

 its height than in man. This elongation may be enormously 

 increased, as in the Great Ant-eater though the prolongation 

 of the muzzle does not necessarily carry with it a similar 

 increase in length of the palatine, as we see in the Dolphin, 

 Globicephalus, where it is comparatively short. 



That the posterior margin of the palate bones should form 

 the antero-inferior border of the posterior nares is a character 

 which man shares with most of his class, and with no other. 

 In some Mammals, however (as we have seen), it is the ptery- 

 goids which perform this function, as in the only Sauro- 

 psidans (Crocodilia) having a palate with a solid bony roof 

 like man's. 



It is the rule, however, that the anterior margin of the palate 

 bones forms the postero-inferior margin of the posterior nares. 

 as we find to be the case in Birds, non-crocodilian Reptiles, 

 and Batrachians, 



This difference of position in the palate bones is owing to 

 the fact that the horizontal, or palatine, plate, and the greater 



