Fig. I. 



A, The skull and vertebral column of the Frog, viewed from the dorsal surface. 

 B, The same from the ventral surface. C, Lateral view of the urostyle ; a bristle 

 is passed through the foramen for the tenth spinal nerve. D, The branchial 

 skeleton of the Frog. (All the figures after Ecker.) O, orbital fossa; pmx, 

 premaxilla ; mx, maxilla; q-j, quadrato-jugal ; na, nasal; pf, parieto frontal ; 

 ex, exoccipital ; fni, foramen magnum ; pro, pro-otic ; sy, squamosal ; sp. et, 

 sphenethmoid ; par, parasphenoid ; pal, palatine ; vo, vomer ; ptg, pterygoid ; 

 av, atlas vertebra ; c, centrum ; ar, neural arch ; zyg, zygapophysis ; trv, trans- 

 verse process; ur, urostyle; H, body of the hyoid; Ha, anterior cornu ; Hp, 

 posterior cornu of the hyoid. 



