415 



more towards the sacrum. The metapophysis is first fully developed upon the seventh dor- 

 sal, and progressively elongates to the last lumbar, where it exceeds the spinous process in 

 length. It presents an articular surface at the under and fore part of its base to be articu- 

 lated with the anapophysis of the antecedent vertebra. These anapophyses increase in thick- 

 ness rather than in length in the succeeding vertebrae, and upon the last dorsal present an 

 articular surface at their under part for connection with a parapophysis. These accessory 

 joints coexist with the ordinary articulations between the anterior and posterior zygapophyses, 

 and there are consequently twelve joints between each pair of vertebrae, in addition to the 

 ligamentous one between the bodies of the vertebrae. This mechanism is designed to give 

 great strength and fixedness to the vertebrae of the trunk in relation to the support of the 

 bony carapace, and to the affording a firm fulcrum or centre to the powerful muscular forces 

 exercised by the limbs in the act of burrowing. The elongated metapophyses have a more 

 direct relation to the support of the carapace, the spinous processes representing the ' king- 

 posts,' and the metapophyses the ' tie-beams ' in the architecture of a roof. The sacral ver- 

 tebrae progressively increase in breadth after the second, to form an extensive juncture with 

 the ischial bones. The tuberosities of the ischia, and similar tuberosities at the fore part of 

 the ilia, bend outwards and upwards, to afford four strong additional supports to the bony 

 carapace : the long diapophyses of the first caudal vertebra abut against those of the last 

 sacral vertebra and the tuberosities of the ischia. The metapophyses reappear upon the 

 second caudal vertebra, and continue to the antepenultimate one, where they are reduced to 

 ridges upon the anterior zygapophyses. 



The posterior dorsal ribs are deeply excavated upon their external surface ; five pairs 

 directly join the sternum, which consists of six bones, a very small one being interposed be- 

 tween the fourth and the long one supporting the ensiform cartilage. The clavicles are com- 

 plete. The acromion is bifurcate, the longest division arching forwards and downwards to 

 meet the clavicle. The humerus is perforate above the inner condyle. The ulna is remark- 

 able for the length and strength of its olecranon. There are four digits on the fore-foot, the 

 two middle much exceeding in length and strength the outer and inner ones. The femur has 

 a third trochanter. The tibia and fibula have coalesced at both extremities. There are five 

 digits on the hind-foot. 



The dental formula is : ^=32. None of the teeth are implanted in the premaxillaries. 

 The chief expansion of the cranium is for the lodgement of the capacious olfactory capsules. 

 The elements of the occipital bone have not coalesced : the superoccipital developes a pair of 

 strong tuberosities at its upper part. 



Mus. Brookes. 



2297. The vertebra dentata and five following cervical, with fourteen dorso-lumbar 

 vertebrae of the Dasypm Apar. 



The spine of the third cervical has completely coalesced with that of the dentata, which is 

 thick and high, but more extended forwards than backwards. The spine of the fourth cer- 

 vical is applied to its back part. The neural arches of the succeeding cervicals have no 

 spines, but form thin transverse bars of bone, which in the middle are incomplete above the 

 fifth and sixth cervicals, upon which the antecedent vertebrae are strongly bent backwards. 



