336 



THE CAT. 



[chap. X. 



Fig. 153. — Outline of the Head and Neck of an Embryo 

 Pig, two-thirds of an inch in length, seen laterally. 

 Magnified seven diajietees. 



Fig. 154.— The Skull of the same Embryo (in its Incipient 

 Stage of DKVKLorMKNT), seen from below. Magnified 



TEN DIAMETERS (VENTRAL ASPECT). 



Tlic following letters indicate the same parts in whichever o 



Ijotli ligiires :— 



e' to c*. The live divisions of the young hrain, 



a. TliL- eye. 



•!!. Tlic nose. 



m. Till' mouth. 



tr. Cartilage of the trahcculsc. 



dr. Cornua traliecularuiii. 



j)U. Prc-nasal CJirtilage. 



jtpij. rton-go-iialatine <'artila;,'c. 



mn. Tin; 'mandibular arch, vith Meckel's carti- 

 lage. 



tc. First visceral deft, whidi becomes tlie tym- 

 liano-Eustachian passage. 



the opposite side toform 

 the lower jaw, while 

 a process grows for- 

 ward and upward from 

 the more proximal 

 part of each first 

 visceral arch, such 

 growth, termed the 

 maxillary process (Fig. 

 152, inps), laying the 

 foundation of the up- 

 per jaw. The two 

 maxillary processes do 

 not, however, join to- 

 gether in front, but 

 both join a median 

 down growth, termed 

 the )iaso-fivntal process 

 (Fig. 152, 7is). This 

 last-named process de- 

 scends from the front 

 end of the floor of 

 the incipient cranium, 

 and has on each side 

 of it one of the two 

 depressions which are 

 the incipient olfactory 

 sacs. Its lower end 

 forms the middle of 

 the front of the upper 

 jaw, while the max- 

 illary processes which 

 unite with its distal 

 end, on each side,form 

 the sides of the upper 

 jaw. The interval left 

 on each side (above 

 the junction of the 

 naso-i'rontal and max- 

 iUary processes,) forms 

 the nasal passage, and, 

 in part, the lachrymal 



f the above figures they occui-, or in 



an. The auditory vesicle. 

 hji. The lerato-hyoid arch. 

 Ir (1 to 4). The I'lranchial bars and clefts. 

 ihh. The thyro-hyoid. 

 jitj. The pituitary fossa. 



cli. The notochord in the cranial basis, sur- 

 rounded l>y the investing mass (iv). 

 VII. Facial nerve. 



IX. Glosso-pharyngcal. 



X. Pneuniogastrie. 

 XII. Ilypo-glossal. 



