i 3 o THE SKULL [CHAP. 



but the name ethmoturbinal, applied to it by Sir Richard 

 Owen, is perhaps more appropriate. 



The uppermost of the lamellae of the ethmoturbinal, lying 

 immediately under the nasal bones, is rather distinct from 

 the others, and extends much further forwards ; and as in 

 certain Mammals it becomes united by bone with the 

 nasal, it is sometimes distinguished under the name of 

 nasoturbinaL 



In front, and on a rather lower level, a similar, but smaller 

 and less complex bone (AfT), consisting chiefly of horizontal 

 lamellae, is placed. This, though originally developed from 

 the same cartilage lining the outer wall of the nasal chamber 

 as the last, ossifies quite distinctly from it, and contracts a 

 bony union by a horizontal lamella on its outer side with 

 the maxilla. This is the maxiUoturbinal, and corresponds 

 with the " inferior turbinated bone " of human anatomy. 



It will be observed, that while the ethmoturbinal is placed 

 high in the nasal cavity, and above the direct channel by 

 which the air passes to the posterior nares, the maxiUo- 

 turbinal, situated nearer the front of the chamber, before it 

 has divided into an upper true olfactory chamber and a 

 lower narial passage, nearly blocks up the whole cavity, so 

 that air passing through in inspiration is filtered between its 

 meshes. The moist membrane which covers its bony plates 

 in life is supplied with nerves chiefly from the fifth pair, 

 and not from the olfactory ; so that it does not perform the 

 function of an organ of smell like the ethmoturbinal, but 

 rather serves to guard the entrance of the respiratory 

 passages from foreign substances, and perhaps to warm the 

 inspired air. 



In describing the walls of the cranium, a large space was 

 mentioned on each side, between the posterior and middle 



