U6 



Boyal Suciefi/ : — 



first time, the student of the morphology of the skull was provided 

 with a criterion of the truth or falsity of his speculations ; and that 

 criterion was shown to he Development. 



My present ohject is to lay before you a brief statement of some 

 of the most im])ortant results to which the following out of the Hues 

 of inquiry opened up by these eminent men seems to lead. Much 

 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 j)articularly to the recent admirable essays of Prof. Goodsir 

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

 ])ulse 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 

 aflfirmatively — so far, at any rate, as the osseous cranium is concerned. 



[The author describes the general arrangement of the bony elements 

 in the cranium of the Sheep, and proceeds to compare it with that of 

 tlie Bird.] 



Composition of the Shill of a Bird (fig. 1). 



Fig. 1. — Longitudinal section of the Skull of a 

 In this and the following sections of Crania the letters 



13.0. Basioccipital. 

 B.S. Basisphenoid. 

 P.S. Presphenoid. 

 Eth. Ethmoid (lamina per- 



pendicularis). 

 E.O. ExQccipital. 

 M. Mastoid. 

 P. or P.S. Petrosal. 

 P.M. Petromastoid. 



A.S. Alisphenoid. 

 O.S. Orbitosphenoid. 

 Pf. Prefrontal. 

 Sq. Squamosal. 

 Ep. Epiotic. 

 S.O. Siipraoccipital. 

 Pa. Parietal. 

 F. Frontal. 



young Ostrich. 



have the same meaning. 

 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. • 



