VII.] 



THE COMMON FROG. 



lOI 



The muscles of the abdomen may be conceived as 

 having arisen through atrophy, in that region, of the 



Fig. 64.— Diagram of Caudal Muscles of Right Side or Tail of Iguana, showing 

 how the ventral mass resembles the dorsal part, and how the tendinous inter- 

 sections of the mu cular fibres are drawn out into cones. N, neural spine; 

 11, hypapophysial spine ; z, zygapophysis ; /, transverse process ; i, dorsal series 

 of cones ; 2, upper lateral series of cones ; 3, lower series of cones ; veuLral series 

 of cones. 



separating membranes and subsequent sphtting up of 

 the muscular mass into super-imposed sheets of 

 differently-directed fibres. 



This filiation between piscine and mammalian 

 myology could hardly have been detected but for the 

 remarkable series of gradations which the frog's class 

 exhibits — gradations both between species, and be- 



Fig. 65.— Muscles of th= Right Side of the Tongue of Man. i, styloglossus ; 

 2, stylo-hyoid : 3, stylo-pharyngeus ; 4.. hyo-glossus ; 5, genio-hyoid ; 6, genio- 

 glossus ; 7, linguaiis. 



tween different ages and conditions of one and the 

 same species-. 



The muscles connected with the human lingual 

 apparatus are sufficiently complex. One such muscle 



