306 MAMMALIAN ANATOMY 



upper is the larger. The anterior end of the lower scroll runs under 

 the partition (3). 



The inner surface (Fig. 230), as a whole, is convex in both direc- 

 tions, and is applied to the upper posterior part of the fourth piece 



FIG. 229. 



^jjSfc~ Attachment to Cribriform Plate. 

 Fourth Outer Scroll, 3'. -y^^^5^"(/ Outer Scroll, 3". 



%> 

 THIRD PIECE OF LATERAL ETHMOID, OUTER ASPECT. 



(Fig. 220, 4'). The bowed superior surface is opposite the concave 

 lower surface of the second piece. 



The fourth piece may be considered as forming the axis of the 

 lateral ethmoid, supporting on each side, but particularly on the outer 



FIG. 230. 



f -~ 



Attachment to Cribriform Plate. - 

 Opposite Outer Surface of Fourth Piece.- 



THIRD PIECE OF LATERAL ETHMOID, INNER SURFACE. 



side, the other smaller pieces, and expanding in front to produce the 

 external and internal masses of more delicate scrolls (Fig. 221). 

 Only the posterior part of its median partition (4) and a variable amount 

 of the root of the lower scroll (4") appear on the posterior quadrate 



FIG. 231. 



Opposite Inner Surface <>f Third Piece; sometimes shows as 



Sixth Outer Scroll, 4'. ^ ,,_ 



.Attachment to Cribriform 



Floor of Ethmoidal Cleft. "' " " PMe - 



External Anterior 

 Smaller Scrolls, it". 



Seventh Outer Scroll, It". 



FOURTH PIECE OF LATERAL ETHMOID, OUTER ASPECT. 



part of the outer surface of the lateral ethmoid (Figs. 222, 231) ; but 

 the strip bordering the ethmoid cleft Behind may be regarded as an 



