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17B) to the back part of the squamosal bone, or 

 bony shell over the back part of the primary upper 



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Fig. 112. Relations of the Parts of the Middle Ear in an 

 Extinct Mammal- like Reptile (after Sushkin). 



For details, see pp. xxxix, xl. 



jaw. In the reptiles the tympanum is always 



associated with this same region and is also more 



or less connected with the angular bone of the 



217 



