584 ANATOMY OF VERTEBRATES. 



confluent. Each moiety, or premaxillary, is reduced to the size 

 required for the lodgment of two vertical incisors. As the canines 

 in Man do not exceed the adjoining teeth in length, and the pre- 

 molars are reduced to two in number, the alveolar extent of the 

 maxillary is short, and the whole upper jaw is very slightly 

 prominent. 



Of the diverging appendages of the maxillary arch, the more 

 constant one, called ' pterygoid,' 24, articulates with the palatine, 

 but coalesces with the sphenoid ; the second pair, formed by the 

 malar, 26, and squamosal, 27, has been subject to a greater degree of 

 modification : this appendage still performs the function assigned to 

 it in Lizards and Birds, where it has its typical, 

 405 ray -like figure, of connecting the maxillary with 



the tympanic, or one rib with the next ; but the 

 second division of the appendage (squamosal), 

 which began to expand in the lower Mammalia, 

 and to strengthen, without actually forming part 

 of, the walls of the brain-case, as in fig. 140, 27, 

 now attains its maximum of developement, and 

 forms an integral constituent of the cranial pari- 

 Frontview^^^Human total ^^^g^ filling up a Very large cavity between the 

 neural arches of the occipital and parietal seg- 

 ments. It coalesces, moreover, with the tympanic, mastoid, and 

 petrosal, and forms, with the subsequently anchylosed stylo-hyal, a 

 compound bone called ' temporal ' in human anatomy. Embryology 

 shows, empirically, the facts of developement: the key to the 

 complex beginning of this •■ cranial bone ' is given by the dis- 

 covery of the general pattern on which the skulls of the verte- 

 brate animals have been constructed. In relation to that pattern, 

 or to the archetype vertebrate skeleton, the Human temporal bone 

 includes two pleurapophyses, 38 and 28, a parapophysis, 8, part of 

 a diverging appendage, 27, and a sense-capsule, I6. 



In the Human embryo the cartilaginous follows the fibrous stage 

 of the brain-case in all the neurapophyses, viz. : exoccipitals, ali- 

 sphenoids, orbitosphenoids, prefrontals. The latter already show 

 their lateral confluence, closing the cranium anterior to the multi- 

 perforate part for the divisions of the olfactory nerve, called ' cribri- 

 form plate of the ethmoid,' and forming the ' crista galli ' above, 

 and the ' lamina perpendicularis ' below, that plate ; in connection 

 with which are the ^ turbinal ' capsules, or supporters of the ^ sense- 

 organ,' which are also cartilaginous. The chondrified bases of 

 the alisphenoids descend into the basisphenoid. The exoccipital 

 cartilage ascends into the lower half of the superoccipital. The 

 cartilaginous capsule of the ear-organ also sends a thin plate to 



