1008 OF GENERATION. 



1012. Within the Cranio-spinal canal thus formed, the rudiment of the Cere- 

 bro-spinal axis is found, at first under a very different aspect from that which 



Parapophyses ; Mastoid portion of the Temporal bones. 

 Neurapophyses ; Great wings of Sphenoid bone, or Ali-sphenoids. 

 Neural Spine; Parietal bone.s. 



III. PROSENCEPHALIC OB FRONTAL VERTEBRA. 



Centrum ; Pre-sphenoid, or body of the anterior or spheno-orbital part of the Sphe- 

 noid bone. 

 Parapophyses ; External angular processes of Frontal bone (the post-frontals of 



Fishes). 



Neurapophyses ; Small wings of Sphenoid bone, or Orbito-sphenoids. 

 Neural Spine; Frontal bone. 



IV. RHINENCEPHALIC OR NASAL VERTEBRA. . 



Centrum; Vomer. 



Neurapophyses; Ossa plana of Ethmoid bone. 

 Neural Spine ; Nasal bones. 



In connection with the foregoing, we have two ossified " sense-capsules ;" the Auditory 

 formed by the petrosal portion of the Temporal bone; and the Nasal formed by the prin- 

 cipal part of the Ethmoid bone, with the turbinate bones. 



The hcemal arches of the cranial vertebrae form the bones of the Face and of some other 

 parts, as will be seen from the following table : 



TABLE II. 



Composition of the Hcemal Arches of the Cranial Vertebrce, in Man. 

 I. EPENCEPHALIC OR OCCIPITAL VERTEBRA. 

 Pleurapophyses ; Scapulae. 



Diverging Appendages ; Bones of Arm, Forearm, and Hand. 

 Hcemapophyses ; Coracoid processes of Scapulae (Coracoid bones of Oviparous 



Vertebra ta). 

 Hcemal Spine ; Deficient. 



[The Clavicles and first segment of the Sternum, which complete the Scapular arch 

 in the Mammalia, are regarded by Prof. Owen as the haemapophyses and haemal 

 spine of the atlas, or highest vertebra of the trunk.] 



II. MESENCEPHALIC OR PARIETAL VERTEBRA. 



Pleurapophyses ; Styloid processes of Temporal bone. 

 Diverging Appendages ; Greater cornua of Hyoid bone, or Thyro-hyals. 

 Hcemapophyses ; Lesser cornua of Hyoid bone, or Cerato-hyals. 

 Hcemal Spine ; Body of Hyoid bone. 



III. PROSENCEPHALIC OR FRONTAL VERTEBRA. 



Pleurapophyses ; Tympanic portion of Temporal bone. 

 Diverging Appendages ; Deficient. 

 Hcemapophyses ; Articular portion of Inferior Maxilla. 

 Hcemal Spine ; Dental portion of Inferior Maxilla. 



IV. RHINENCEPHALIC OR NASAL VERTEBRA. 



Pleurapophyses ; Palatine bones. . 



Diverging Appendages ; Pterygoid and Malar bones, with squamosal and zygomatic 



portions of Temporal bones. 

 Hcemapophyses ; Superior Maxillary bones. 

 Hcemal Spine ; Intermaxillary bones. 



Thus we see that, in the anterior segment, we have the highest development of the visceral 

 portion, coexisting with the lowest development of the neural ; this last being obviously 

 related to the comparatively low development of the ganglionic mass which it is destined to 

 protect. The development of the soft parts of the face takes place in conformity with that 

 of the vertebral segments; these being formed by "visceral arches" which meet on the 

 median line (Fig. 270, c, d d} ; and the knowledge of this fact enables us to explain those 

 congenital malformations which result from want of union of the two halves on the median 

 plane, such as cleft palate and harelip. 



