386 



of what I have to say is directed towards no other end than the revival 

 and justification of their views a purpose the more worthy and the 

 more useful, since with one or two honourable exceptions I allude 

 more particularly to the recent admirable essays of Prof. Goodsir 

 later writers on the Theory of the Skull have given a retrograde im- 

 pulse to inquiry, and have thrown obscurity and confusion upon that 

 which twenty years ago had been made plain and clear. 



I have said that the first question which offers itself is, whether 

 all vertebrate skulls are or are not, constructed upon a common plan, 

 and in entering upon this inquiry I shall assume (what will be 

 readily granted), that if it can be proved that the same chief parts, 

 arranged in the same way, are to be detected in the skulls of a 

 Sheep, a Bird, a Turtle, and a Carp, the problem will be solved 

 affirmatively, so far, at any rate, as the osseous cranium is con- 

 cerned. 



Composition of the Skull of a Sheep (fig. 1 ). 



S.O- 



Fig. 1. Longitudinal section of the skull of a sheep. In this and the following 

 sections of Crania the letters have the same meaning. 



B.O. Basioccipital. 

 B.S. Basisphenoid. 

 P.S. Presphenoid. 

 Eth. Ethmoid (laminaper- 



pendicularis). 

 E.G. Exoccipital. 

 M. Mastoid. 

 P. or P.S. Petrosal. 

 P.M. Petromastoid. 



A.S. Alisphenoid. 

 O.S. Orbitosphenoid. 

 Pf. Prefrontal. 

 Sq. Squamosal. 

 Ep. Epiotic. 

 S.O. Supraoccipital. 

 Pa. Parietal. 

 F. Frontal. 



Foramina for nerves. 

 1. Olfactory ; 2. optic ; 3 

 & 4. oculomotor and pa- 

 thetic nerves; 5. third 

 division of trigeminal ; 

 7. portio dura and mol- 

 lis ; 8. pneumogastric ; 

 Epiph. Pineal gland, or 

 epiphysis cerebri. 



