520 



Tlir; RABBIT 



arising iVoni the wall of the tympanic cavity and inserted on 

 to the manubrium of the malleus. 



The study of development indicates that the malleus corresponds to 

 Lhc articular part of Meckel's cartilage of lower Vertebrates, and the 

 incus to the quadrate (|i. 44) : the arliculation of the bony mandible 



Cch 



t'lr;. 1^3. — Diagram of the mainmalian bony labyrinth, tympanic cavity, and external 

 auditory passage. 

 Cell, bony cochlea ; E. Eiistacliian tube ; F..r. external auditory passage : /-. bony 

 semicircular canals ; I\l. tympanic membrane ; N. auditory ner\e ; 0^. st.apes ; 

 t'-. incus ; 0^. malleus, (.'\fter Headle;'.) 



with the squannjsal in Mammals h;\s rendered these parls unnecessary 

 for their original purpose, and they have undergone a change of function, 

 forming an accessory part of the auditory apparatus. 



Urinogenital Organs. — 'llie kidiwys (Im'o. 125, k) are of a 

 sfimewhat coiiipressed, oval shape, witli a notch or hiliii on 

 the inner side. They are in close contact with the dorsal 

 wall of the abdominal cavity, the right being somewhat in 

 ;id\ani;e "f the left. 'lYiwards the hilus, the tubules of 



