16 ANATOMY OF THL; HORSE. 



channel, open superiorly, and that in the four or five subsequent 

 pieces into a simple groove; until at length all traces of such 

 formation disappear. 



Trtferior S^/r/ctce— Concave. The first bone possesses breadth 

 and flatness inferiorly, the same as a lumbar vertebra : the 

 others display less and less of the vertebral character back to 

 the fifth or sixth, after which they present angular borders. 

 Into these parts are inserted the depressores coccygis. 



Lateral Borders. The three or four anterior bones have trans- 

 verse processes, increasing in length with their priority ; which 

 give attachment to the sacro-sciatic ligaments, and also to the 

 curvatorcs and compressores coccygis. The fifth and subse- 

 quent bones are nothing more than cylindrical forms, and differ 

 in little else than in a regular respective diminution in volume. 



Base — Presents an oval surface for articulation with the end 

 of the sacrum ; and also two little articulatory processes, receiv- 

 ing between them correspondent sacral eminences ; and below 

 these processes two notches, for the transmission of the fifth pair 

 of sacral nerves. 



Apex — Obtuse and rounded. 



THE HIP, HAUNCH, OR EDGE BONES. (OSSA 1 N N OM 1 N ATA *. ) 



Situation. Forming the lateral and inferior parts of the pelvis. 



Form. Very irregular : large and flat; broad at the extre- 

 mities, which turn in different directions ; middle portion con- 

 tracted. 



Division. Into two surfaces and four borders. 



J'he External or Dorsal Surface — Divided by the contracted 

 portion in the middle into two parts. The anterior part, also 

 distinguished as the dorsum ilei, is even and smooth, slightly 

 concave, triangular in figure, and faces outwards and back- 

 wards : it affords attachment to the glutei, maximus et in- 

 ternus. — The posterior division presents, outwardly, the ace- 

 tabulum or cotyloid cavity, hemispherical, nearly three inches 

 in diameter, looking outwards and downwards, surrounded 

 by a prominent lip of bone which is interrupted below by 

 a notch, and having a roughened depression in its middle 

 into which is implanted the round hgament confining the 

 head of the os femoris within the cavity ; above and in front 

 of the acetabulum the bone is depressed and roughened in two 

 places from which takes root the bifurcated tendon of the rectus 



* Literally, unnamed bones ; but answering to the other English appella- 

 tions. 



