438 ANATOMY OF VERTEBEATES. 



second ribs meet at an acute margin below : they are formed as 

 in tlie preceding vertebra. In the fourth dorsal vertebra, the 

 spine is still more remarkable for its height and strength: the 

 vertebral body has a greater antero-posterior thickness, but the 

 anterior and posterior costal surfaces still meet below. A larger 

 proportion of these surfaces is contributed by the neurapophyses. 

 In the ninth dorsal vertebra, the posterior costal surfaces, which 

 are almost exclusively formed by the neurapophyses, are separated 

 by a non-articular tract from the anterior ones. 



The sixteenth dorsal vertebra shows only a single pair of costal 

 surfaces, which are wholly formed by the neurapophvses : the 

 metapophyses are well developed. In the remaining dorsals the 

 costal surfaces decrease in size. The first and second ribs are 

 almost straight, and expand to join their short sternal parts : as 

 the ribs lengthen, they ]n-eserve their slenderness, and are straighter 

 at their lower halves than usual : the vertebral third is bent, sub- 

 cyKndrical, and grooved anteriorly. The lumbar diapophyses are 

 short and depressed. The neural spines of the dorso-lumbar 

 series incline backward, gradually decreasing in height, and in- 

 dicate no centre of inflexion in the capacious well-ribbed trunk. 

 The thick sides of the three sacrals which join the ilia consist of 

 pleurapophyses which coalesce with both centrum and neural 

 arch. The neural spine subsides after the seventh or eighth 

 caudal : diapophyses continue to the twelfth, and zygapophyses 

 to the fifteenth : the rest are reduced to the centrum. 



B. Shidl. — The cranial much exceeds the facial part in size : 

 its upper part forms an expanded dome: but a section, as in 

 fig. 296, shows that the cavity for the brain occupies but a small 

 proportion of the back part of the dome's base : the rest being 

 formed bv air-sinuses, bounded bv plates of bone, extendinof 

 between the remote outer and inner * tables * in the form of sinuous 

 plates so disposed as to give greatest strength with least material. 

 The occipital condyles are small, approxhnate below, and project 

 backward from the upper half of the posterior surface of the 

 skull. The occipital slopes as it rises to curve forward to the 

 vertex, and more so in the African than in the Indian species. 

 The position of the epencephalic compartment of the cranium, 

 fig. 296, t\ the suspension of the malar bone, fig. 29o. 2(3. in the 

 middle of the zygomatic arch, the size and connections of the 

 premaxillaries, 22, and their deep and large alveoli for the single 

 pair of incisors, recall characters of Rodentia. The cranial sutures 

 become obliterated ; but examination of the skull of a very 

 young Elephant (Indian) has enabled me to give the following 



