312 



THE RABBIT 



(/) The pes or foot, consisting of four long metatarsals and four digits or 

 toes. The first or preaxial digit is vestigial or absent. Each digit has 

 three phalanges, and the last phalanx is modified to support a claw. 



Make a sketch of the hind-limb. 



Great trochanter 



Tibia- 



Head 



-Fibula 



Lesser 

 trochanter I 



Femur- 



Calcaneat process- 

 Third trochanter 



Astragalus- 

 Navicular- 

 Mesocuneiform 

 Ectocuneiform 



Metatarsals--'- 



Phalanges- 



Fie. 105. — The Rabbit {Lepus cunictilus). A. Left Femur or Thigh-bone ; B. Left 

 Tibia-fibula ; C. Left Tarsus (ankle) and Pes (foot). 



Compared with the Bird skeleton that of the Mammal shows the following 

 important differences : — 



The sutures between the bones of the skull are generally persistent. 



The cranial cavity extends between the orbits into the interorbital septmu. 



The internasal septum is produced in front of the nasal bones, and forms the 

 cartilaginous support of a flexible nose or muzzle. 



There is a tympanic bone around the outer ear. 



The otic bones (auditory capsule), are united to form a periotic, which is 

 fused with the squamosal. 



There are three ear ossicles (malleus, incus, stapes). 



The skull has two (ex-occipital) condyles. 



The lower jaw articulates on the squamosal. The quadrate is absent. 



Each ramus of the lower jaw consists of a single bone (the dentary). 



The jaws have teeth ; and the teeth are specialised, are typically heterodont, 

 i.e., different in form and in function. 



The vertebral centra, and also the long bones, usually have epiphyses. 



