24 THE AMERICAN MONTHLY [Jan. 



the exoccipitals are developed. Bones reach out from 

 the brain-case and support tliedifFerent parts of the face, 

 posteriorly arc the auditory ca-psules surrounding the ears; 

 when bones are developed in this cartilage they are 

 called otic bones and in the frog pro-otic-s are formed on 

 the anterior side of the cartilage. A mass of cartilage 

 quadrate cartilage reaches from the occi})ital region side- 

 ways as far as the angle of tlie jaw. A bone the pterygoid 

 ossifies in connection with this. It reaches forward and 

 helps to ioYxw the uj)per jaw. It also rests against the 

 sphen ethmoid cartilage. 



Another bone related to the hinder part of the skull is 

 the quadrato-jugal, this forms the hinder outer angle of 

 tlie head, and \\\<i glenoid cavity^ where the lower jaw 

 articulates, i.s located in it. The arch running forward 

 from the quadrate forming the hinder part of the upper 

 jaw is called the zygomatic anh the space between it and 

 the brain case is the orbito- temporal fossa, and lodges the 

 eye, in front and the temporal muscles (used in closing the 

 lower jaw) behind. Continuing on the line of the iipj)er 

 jaw, you will find next in front of the zygomatic arch 

 a slender portion of the maxillary bone. This bone presents 

 two other portions; one on the roof of the skull and he- 

 hind the nostril, the facial portion: and a second part 

 which runs in and forms a part of the roof of the mouth 

 chamber, in front, the palatine portion. The middle of 

 the upper jaw is formed by the pre-maxillaries^ which 

 also form the lower border of the nostril. 'Y\\%. nasal 

 bones, run from the premaxillaries to the frontal.s in the 

 middle line of the roof of the skull, and are located pos- 

 terior to the nostrils. Small bones, i\\<d pre-frontals cora- 

 plete the closure of the nostril, I n the roof ot the mouth 

 there are in front two laige flat bones, vomers and crossing 

 the capito-temporal fossa. Between the vomer and the 

 maxillary are the palatines. The lower jaw is composed 

 of 'jartilage in early stages but in adults a number of dif- 



