LECT. iv.] NATURE'S AMPUTATIONS. 109 



(" Mecke!' s cartilage"), which is the lower portion of the 

 primary or deep mandible or lower jaw of the Reptile or 

 Bird. 



The upper part of the primary jaw becomes the 

 malleus (hammer), and the swinging-piece, called " quad- 

 rate " in the oviparous types, becomes the incus (anvil). 

 The topmost segment of the second or hyoid arch is, as 

 I said before, the stapes (stirrup). 



In the embryo of the Pangolin and Sloth, the stapes 

 is a solid cartilage ; in the latter it acquires a small hole 

 after it becomes bony ; it is solid also in the Ant- 

 eaters. 



In Armadillos it is sfaVrMp-shaped from the first ; thus 

 showing a greater nearness to the higher Mammalia, 

 whilst the others show a nearer affinity to the Mono- 

 tremes, or Prototheria. 



I shall describe the peculiar transformation of the 

 jaws more at large when I come to the Insectivora (the 

 Mole and his relatives). 



ADDENDUM TO LECTURE IV. 



From among the various works on Zoology and Anatomy that 

 appear from time to time I may make a few references, especially 

 from those that relate to the forms treated of in the foregoing Lecture. 



I shall merely give the titles of memoirs and papers that have 

 been of most service to me in my own recent researches into the 

 structure and relations of the Edentata. 



