PLATE in. 



Ear Bones of Oppossum. 



Fig. I. — Section of malleus and body of incus. Drawn with Abbe's 

 camera lucida, multiplied 200 times. 



Fig. 2. — Model of ear bones, multiplied 175 times. The model was 

 made in three pieces, although segmentation was not yet complete. 

 The lines of future division are, however, very distinctly indicated 

 in the sections, as seen in Plate III, Fig. i. 



(112) 



