The Frog — An Amphibious Vertebrate Animal 423 



tection and serves for sensory purposes. The pigment bodies are respon- 

 sible for some protective coloration. 



The bony endoskeleton (Fig. 210) consists of (1) an axial skeletoti 

 (skull and vertebral colum?i) and (2) appendicular skeleton (pectoral 

 girdle with its forelimbs and pelvic girdle with its hindlimbs). The frog 

 has no ribs. Most of the bones of the skull, except those of the upper 



Premaxilh- 



Maxilla 



Sphehothmoid 



fronbopaneba} 



Squamosal 



Atlas or /sfc cer- ^ 



v'lcal vertebra 



Transverje process, 

 of vertebra 



Jn^ -Phalanges 



Metacarpals 



^y Carpals 



Radioulna 



Prootid 



Humerus 



— Suprascapula 

 — Sacral or 9^ vertebra 



Urosiyle 

 Ilium 



hchium 



Acetabulum 



— femur 



--.Tihiofibula 



~--Asbraqa\us 

 Colcar 



Calcaneum 



Tarsals 



Metatarsals. 

 Phalancjes 



Fig. 210. — Skeleton of frog (dorsal view, appendages of left side not shown). The 

 acetabulum is not a bone but the joint at the proximal end of the femur. 



and lovuer jaws and the hyoid bone to which the tongue is attached, form 

 the brain case (cranium). The brain and spinal cord connect through 

 a large opening (foramen magnum) at the base of the cranium. The 

 cranium articulates with the first vertebra (atlas) by means of a pair of 



