THE BONY TRUNK. 77 



sacrum fits. Before articulating with the forward part of 

 the sacrum its most anterior portion constitutes the pro- 

 jecting hip of the Iiorse (Skel. 9, 9). A Httle lower, and 

 more backward than the joint of the spine {Skel. 10) , lies the 

 cup for the reception of the head of the femur, or the round 

 bone, as it is termed by jockeys {Skel. d) ; and its hinder- 

 most part projects backwards, forming the points of the 

 rump {Skel. c, c). The interior of this bone contains im- 

 portant organs ; within it are held the rectum ; the urethra 

 of the male, and the vagina of the female ; a portion of the 

 bladders of each, with the womb of the mare. All of these 

 are vital organs ; for on the proper performance of the 

 functions of each life itself depends. 



It is as well, having stated our own views, to describe 

 those entertained by most anatomists. The ilium is the 

 most forward, broadest, and highest portion of the innomi- 

 nata {Skel. a). It has two spines ; a superior, which lies 

 close to the sacral spine, and an inferior, somewhat more 

 forward than the last {Skel. 9, 9). The ilium, and all the 

 other bones composing the haunch, are supposed to meet 

 about the cup of the round bone {Skel. d). The pubis {Skel. 

 h) forms the floor of the pelvis, and the ischium is the most 

 posterior portion {Skel. c, c). Its two projecting promi- 

 nences being designated the spines of the ischium. 



To complete the spine there remain the tail bones to be 

 enumerated {Skel. 7, 7, 7, &c.). These at first bear some 

 resemblance to vertebrse, but ultimately dwindle to very 

 thin and short round pieces of bone, like to little pieces of 

 hollow stick. They, however, possess one peculiarity ; the 

 two bones in apposition do not fit one into the other by means 

 of a shallow cup and ball joint, but each meets the next by 

 a rounded kind of projection, and nothing can be imagined 

 better calculated to facilitate perfect freedom and play of 

 action than two balls meeting together. Hence, we can 

 easily comprehend how the tail is enabled to be switched 

 about in every direction without fear of dislocation. 



The neck always consists of seven bones. In animals 

 with the longest and the shortest necks this holds good ; 

 the number of bones forming the neck of any animal is 

 never more than seven. Creatures of the sloth species used 



