VII " 



'■"^yuV^ 



Tim IV V vn'^^viii' 



Fig. 49. — Morphology of. the visceral skeleton. A, shark; B, amphibian; 

 C, reptile; D, mammal; the successive arches are indicated by Roman 

 numerals; the dorsal and ventral parts of arches I and II are indicated by 

 exponent letters, d and v. lb, labial cartilage; s, spiracular cartilage; o, 

 operculum; VII -^ and VII ^ are the arytenoid and tracheal cartilages, re- 

 spectively. (From Wilder's History of the Human Body, with the permis- 

 sion of Mrs. H. Hs Wilder and Henry Holt and Company.) 



74 



