THE SKELETON. 79 



22. How do you distinguish the distal from the proximal end of the 

 metacarpals? 



23. Describe the variation in the number of metacarpals in mammals. 



24. Describe the usual arrangement of the phalanges in mammals 

 having five digits. 



25. How do you distinguish a phalanx from a metacarpal? 



26. Give the number of functional digits in forelimb of dog, pig, cow, 

 sheep, horse, and rabbit. 



27. Name some mammals with atrophied digits. 



28. What is the significance of these? 



29. In the evolution of the perissodactyls (odd-toed ungulates) de- 

 scribe the order in which the digits are lost. 



30. In the Bovidae and Cervidae which two digits are functional? 



THE PELVIC LIMB. 



The pelvic or hind-limb of the cat is composed of the 

 innominate bone, femur, patella, tibia, fibula, seven 

 tarsals, five metatarsals, and twelve phalanges. 



The innominate bone is composed of four parts, the 

 ilium, ischium, pubis (Figs. 21 and 38), and the small 

 cotyloid bone. The ilium is the dorsal portion, extending 

 down to and occupying about one-third of the acetabu- 

 lum. The ischium includes the caudal portion of the 

 bone, extending ventral and forming two-thirds of the 

 boundary of the obturator foramen. The pubis is the 

 ventral portion, possessing two rami, one projecting 

 laterad to unite with the ilium, cotyloid, and ischium, 

 and the other projecting caudad along the mid-ventral 

 line, joining its fellow and the ischium. In young kittens 

 the junction of these parts is plainly visible, but in adult 

 specimens it is wholly obliterated. In old specimens the 

 ischium and pubis become more or less anchylosed with 

 their fellows in the mid-ventral line. The cephalic and 

 dorsal border of the ilium is the crest (Fig. 39). The 

 rough crescentic area on the mesal aspect is the auricular 

 surface for articulation with the sacrum. The cephalic 



