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ANATOMY OF THE HORSE. 
Development, In the young subject this bone consists of five 
distinct and separable pieces, united, one to another, by a fibro¬ 
cartilaginous substance which in the adult is converted into 
bone. 
THE TAIL-BONES. (oSSA COCCYGIS.) 
Situation, Behind the sacrum, to which the coccyx forms an 
appendix. 
Form, Conical, elongated, and more or less curved. 
Conformation, The coccyx or tail is constituted of several 
small bones resembling vertebrae, varying in size and develop¬ 
ment, and also in number from thirteen to eighteen. 
Division, As a whole, the coccyx presents for consideration 
two surfaces, two borders, a base, and an apex. 
Superior Surface —Convex. The two and sometimes three 
first bones possess complete bony arches, from which arise-one 
or two spinous eminences giving attachment to the erectores 
coccygis, and consequently they possess an entire spinal canal ,* 
in the following two or three pieces, the spinal arch becoming 
gradually more defective, the closed canal degenerates into a 
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. 
Inferior Surface —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 w’hich 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 
curvatores 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 off. 
THE HIP, HAUNCH, OR EDGE BONES. (oSSA INNOMINATA=^.) 
Situation, Forming the lateral and inferior parts of the pelvis. 
Literally, unnamed bones; but answering to the other English appellations 
