FISCHER ON THE PELVIS OF THE MAMMALIA. 23 



number is 18 ; the eight anterior are the longest. The first and second 

 coccygeal vertebrae are composed of a body, a spinous process, and two promi- 

 nent transverse processes. Through these, and through the third, fourth, and 

 fifth vertebrae, the vertebral canal is prolonged, and there it terminates. The 

 last vertebras have no spinous processes, but only small tubercles in their 

 place. The coccygeal vertebrae ought to be divided into two distinct classes, 

 not only in the genus Equus and Simia, but in all mammal quadrupeds : into 

 the perforated, which contribute to the formation of the pelvis and contain 

 the termination of the medulla ; and the imperforated, which form the more . 

 distinct tail. The former are shorter than the latter, but for the most part 

 have spinous processes, often transverse processes, and always oblique pro- 

 cesses ; the posterior coccygeal vertebra are elongated, and in place of pro- 

 cesses, in every genus of animals with tails, have merely tubercles around the 

 articular surfaces. Man evidently wants the first kind and has the second. 

 (Autenreith.} / 



Section 24. Ossa innominata. These bones in the young horse, as in all 

 other mammals, are composed of three the os ilium, ischium, and pubis. The 

 os ilium is triangular, and outwards from that angle which is distant from the 

 sacrum, is bent ; the external aspect is concave and without tubercles : the 

 internal on the other hand, regarded as a whole, is convex, and hence from 

 the middle of the crest of the illium, as far as the superior spine, it is full of 

 tuberosities and impressions ; at this part the os ilium unites with the sacrum. ' 

 Towards the lower part of the os ilium, almost about the middle of its inner 

 surface, a line begins to be formed, which passes obliquely as far as the inner 

 surface of the os pubis, and there terminates ; by which line the pelvis is divi- 

 ded into a greater, or anterior, and a smaller, or posterior, according to the 

 nomenclature of these parts in man. In the horse, the abdominal portion of 

 the os ilium is so small, that the greater pelvis can scarcely be described in 

 that animal. (Autenreith.) The crest of the os ilium is not convex, but runs 

 almost in a straight line as far as the two tubercles, then suddenly contracts, 

 and descending again terminates in other two tubercles. The superior and 

 inferior margins of the os ilium are much excavated. The os ilium of the 

 horse is remarkable for its length, when compared with the horizontal 

 branches of the pubis which form the inferior margin of the pelvis, hence it 

 happens that in this very ample pelvis the acetabula and thigh-bones are never- 

 theless sufficiently near each other, and in this large animal a small space only 

 is observed between the thighs towards the lower part of the belly. (Auten* 

 reith.) The external surface of the os pubis is convex, the internal, concave. 

 It is divided into an anterior branch and a posterior. The anterior ramus has 

 a prominent line on its anterior margin, but more towards its internal surface, 

 however, which is called the crest of the pubis. In the anterior margin there also 

 arise on each side two prominences, which are called the spines of the pubis. 

 The posterior margin of the anterior ramus assists in the formation of the 

 foramen ovale. The external surface of the posterior ramus is convex, the in- 

 ternal, concave ; the external margin of this ramus forms the largest portion 

 of the foramen ovale, The os ischium may be divided into a body and two 

 branches, and it is very large when compared with the os pubis ; its upper ramus 

 forms by its internal concave margin the external border of the foramen ovale. 



