ANATOMY OF THE BEAVER. 6l 



temporal fossa. Although the sutures of the beaver's 

 skull become consolidated early, and are sometimes 

 made out with difficulty, the two sphenoidal wings 

 can be traced in many skulls. In a young skull, 

 after the temporal and parietal are removed, the 

 broad squamous suture which connects the two wings 

 can be opened. Cuvier says: "Le sphenoide pos- 

 terieur touche un peu dans le tempe au frontal"^ T. 

 R. Jones, art. Rodehtia in Cyc. of Anat. and Phys.,^ 

 adopts Cuvier's description of the sphenoids. In 

 forming the suture, the wing of the post-sphenoid is 

 anterior, but the other wing rises higher to join the 

 frontal — the suture of the frontal passes back some 

 distance under the parietal, but not far enough to 

 touch the posterior wing, although they are closely 

 approximated. In this instance, then, the statement 

 of Cuvier is not confirmed. 



The ethmoid bone has a cribriform body in. the an- 

 terior part of the cavity that lodges the olfactory lobe. 

 It has also a vertical plate and three sets of cells on 

 each side, of which a representation is given (Plate V.); 

 the vertical plate has been removed to show the cells 

 entire. A turbinated bone in each nostril is attached 

 by its base to the sheath of the incisor. It is formed 

 of six or seven thin lamina of bone proceeding from 

 its base and dichotomously subdividing and convolu- 

 ting. This bone has been removed in Plate V. to show 

 the sheath of the incisor. The vomer is represented 

 in the same figure by the lower dotted lines. There 



^ Le9ons d'Anatomie Coraparee de Georges Cuvier, etc. Seconde 

 edition. Paris, 1835 to 1846. 



^ The Cyclopaedia of Anatomy and Physiology, by R. B.Todd. 

 London. 



