CHAPTER XL 



THE SKELETON OF THE FROG 1 (Sana temporaria). 



I. EXOSKELETON. 



The skin of the frog is smooth and quite devoid of scales 

 or other exoskeletal structures. The only exoskeletal struc- 

 tures met with in the frog are : 



1. The teeth, which are most conveniently described with 

 the endoskeleton. 



2. The horny covering of the calcar or prehallux (see 

 p. 167). 



II. ENDOSKELETON. 



The endoskeleton of the adult frog consists partly of 

 cartilage, partly of bone and each of these types of tissue 

 occurs in two forms. The cartilage may be hyaline, as in 

 the omosternum and xiphisternum, or may be more or less 

 calcined as in part of the suprascapula and the epiphyses 

 of the limb bones. The bone may be cartilage bone, or 

 membrane bone. 



The skeleton is divisible into an axial portion consisting 

 of the skull, vertebral column, and sternum, and an appen- 



1 See A. Ecker, Die anatomie des Frosches, Braunschweig 1864, 

 translated by G. Haslam, Oxford, 1889, also A. M. Marshall, The Frog, 

 5th edition, Manchester and London, 1894. 



