LECT. IV.] THE HARD PALATE. 103 



the two Jacobson's organs, probably correspond with 

 the pair of vomers seen in the higher Ganoid fishes, 

 in Snakes, and in Lizards. 



The hind pair help the middle single bone (answering 

 to the ploughshare bone of our skull) to bind together 

 the right and left masses of the ethmoid the "upper 

 and middle turbinated bones." 



In the tooth-bearing forms the hard palate is well 

 developed, and in some Armadillos (Tatusia, or the 

 Tatous) the pterygoids help the upper maxillaries and 

 palatines to form this strong floor; a floor to the nose, 

 but a roof to the mouth. 



In the adult Pangolin the pterygoids do not help 

 to form the hard palate ; the four palate-bones gape 

 a little at the mid-line, and thus the base of the 

 vomer is exposed. This is seen also in the common 

 Cat, and is quite like what is found also in the 

 Green Turtle amongst Reptiles, and in the Falcons 

 among Birds. 



But in the largest and the middle-sized true Ant- 

 eaters (Myrmecophaga jubata, and M. tamandua) 

 the hard palate is extended nearly as far back as 

 the base of the cranium, and this is, as in Crocodiles, 

 due to the additional plates formed by the pterygoid 

 bones. 



In the smallest kind (Cydoturus) these bones are 

 very large, and the posterior nares (hinder opening of the 

 nasal passages) are as far back as in the larger kinds, but 



