1898.] ANATOMY OP PEDETES CAFEEB. 861 



process is missing, but the other two are present. In Dipus the 

 2nd, 3rd, 4th, 5th, and 6th cervical vertebrse have their bodies and 

 arches synostosed. In Pedetes they are all free, although the 2nd 

 and 3rd are so very close together that hardly any movement can 

 be allowed between them. In neither animal is there a foramen 

 in the transverse process of the seventh cervical or a ventral 

 tubercle, although that of the sixth is very prominent. 



The first thoracic vertebra only has half a facet on the cephalic 

 part of the side of the body, because in both animals the head of 

 the first rib articulates as much with the seventh cervical as with 

 the first thoracic. In Pedetes the transverse process of the 10th 

 thoracic vertebra has three processes ; the most anterior forms 

 a facet for the articulation of the 10th rib, the middle one is 

 directed outward and corresponds to the tip of the ordinary 

 thoracic transverse process, while the most posterior projects 

 backwards. 



In the 11th thoracic vertebra the rib still articulates with 

 the anterior of these tubercles, the middle one is reduced in size 

 and the posterior one is lai-ger. In the 12th vertebra the pos- 

 terior tubercle has become much larger and has developed into a 

 well-marked anapophysis or accessory process, the middle tubercle 

 has completely disappeared, but tlie anterior is still present, 

 supporting the 12th rib by a definite articular facet. 



In the 1st lumbar vertebra the transverse or, as it is often 

 called, costal process is seen to correspond in shape and position 

 with the anterior tubercle of the transverse process of the posterior 

 thoracic vertebrse, and the anapophysis with the posterior tubercle 

 of the same. The mamillary process or metapophysis first appears 

 on the prezygapophysis of the 10th thoracic vertebra and increases 

 in size vertebra by vertebra into the lumbar region ; it is quite 

 plain that it has no homology with any part of the thoracic 

 transverse processes. In the lumbar region the anapophyses are 

 very large and rest against the outer side of the prezygapophysea 

 of the next vertebra behind; the prezygapophysis is therefore 

 locked in between the postzygapophysis and anapophysis of the 

 vertebra in front. 



After the seven lumbar vertebrae there are four which are fused to 

 form a sacrum, but only two of these support the ilium, the first 

 forming a much larger part of the articular facet than the second. 

 On the ventral side oE the disc between the 4th sacral and 1st 

 caudal vertebrae there is a single bony spur, about 5 mm. in length, 

 attached by fibrous tissue to the disc ; it lies a few mm. to the left 

 of the median line. Between the first and second caudal vertebrae 

 a small well-marked chevron-bone is present, and this is succeeded 

 by others, the one between the 3rd and 4th being the most 

 prominent. After this the bones gradually shorten and become 

 more and more elongated antero-posteriorly and compressed 

 laterally. Between the 9th and 10th caudal the true chevron-bone 

 ceases, but a pair of bony tuberosities project from the anterior 

 part of the ventral surface of the 10th vertebra ; farther back in 



