402 CHARLES CLIFFORD MACKLIN 



of the septum, as shown in this figure. The two sheets unite 

 below the septum, and in this region, which marks their thickest 

 part, they contain the slender spicules of membrane bone 

 which represent the vomer. Though they are found through- 

 out the extent of the vomer they disappear shortly beyond its 

 extremities. 



Fawcett ('11) in his description of the paraseptal cartilages 

 finds a similar sheet of condensed mesenchyme, and gives to it 

 the name "-suspensory membrane," stating that it envelops 

 the anterior and posterior paraseptal cartilages, and extends 

 between them; further that in the interval between these carti- 

 lages the vomer is developed (following Zuckerkandl '08). I am 

 unable to discover in my model any trace of this "suspensory 

 membrane" in front of the ventral extremity of the vomer, so 

 that it has, obviously, nothing to do in this stage with the support 

 of the anterior paraseptal cartilages; moreover it is not found 

 behind the dorsal extremity of the vomer, and hence cannot func- 

 tion in the suspension of the processus cupularis posterior (pos- 

 terior paraseptal cartilage of Fawcett) which evidently repre- 

 sents the last rudiment of the posterior transverse lamina of such 

 forms as the rabbit (Voit). Furthermore, since the cellular com- 

 position of this membrane is apparently the same as that which 

 forms the membranous anlage of any of the membrane bones, and 

 its situation is that which will be occupied by the future upward- 

 growing vomer, and since the vomer is to be found within its 

 thickened caudal portion, it would appear that it is simply the 

 membranous anlage of the vomer. The term 'suspensory' would 

 seem to be misapplied, since the bony elements enclosed by it 

 cannot be said to be suspended, any more than the early osseous 

 spicules of any other membrane bone may be said to be suspended 

 in their membranous anlagen, and the cartilaginous elements 

 are not enclosed by it; indeed the so-called posterior paraseptal 

 cartilages, as Fawcett himself states, are continuous with the 

 lateral walls of the nasal capsule (fig. 14). Fawcett evidently 

 believes that this membrane once sustained the cartilago parasep- 

 talis communis, of such forms as the rabbit, and that the vomer 

 is a covering bone which surrounds and takes the place of this 



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