206 



ANATOMY OF VERTEBRATES. 



of the frontal, forming the fore part of the roof, c, the basi- 

 sphenoid, forming its back part ; the f cribriform plate and spine ' 

 of the prefrontal completing the roof: b is the nasal plate of the 

 maxillary bounding laterally the anterior aperture ; d, pterygoid, 

 similarly bounding the posterior aperture : the floor of the passage 

 is formed by the prcmaxillary, 7, the maxillary, k 9 and the pala- 

 tine, 6. At the upper part of the outer wall is a thin quadrilateral 



part of the prefrontal sculp- 

 tured by grooves and aper- 

 tures for the olfactory nerves ; 

 the posterior part, f, is a 

 little curved, and leaves a 

 space into which the sphenoi- 

 dal sinus opens. The con- 

 volute, thin, reticulate, bony, 

 and gristly lamina, called 

 ' superior turbinal,' is here 

 attached, below which is the 

 division of the general pas- 

 sage, called ( superior mea- 

 tus.' This is bounded below 

 by a similar longer and larger 

 6 turbinal, ' called ' middle 

 spongy bone' in Anthropo- 

 tomy, but usually less dis- 

 tinct from the upper part of 

 the ' ethmo-turbinal ' in lower Mammals. The part of the passage 

 between the middle and lower turbinal is the c middle meatus,' 

 into which the *■ antrum ' or maxillary sinus opens. The lower 

 turbinal is the largest of the three, and longest retains its indi- 

 viduality : below it is the f inferior meatus,' Tt, into which the 

 lacrymal canal opens. 



In most lower Mammals there is a turbinal process from the 

 frontal and nasal bones ; which, from its relative position in their 

 horizontally elongated nasal chamber, is called the ( superior 

 spongy bone ' (oberste muschel, Gurlt), by Hippotomists ; it is 

 not the homologue of that so called in Anthropotomy. 



At the floor of the lower meatus, close to the premaxillo- 

 m axillary ridge supporting the fore part of the septum, is a 

 depression or groove lined by a glandular tract of the pituitary 

 membrane which, in Ungulates, is extended upon a long and 

 narrow gristly sheath at that part, and communicates with the 

 palate by the foramen incisivum. From one to three of the 

 septal branches of the olfactory, traceable from a yellowish grey 



View of tlu; outer wall of the nasal cavity on the right 

 side. 



