S8 Mammalia. SectoriaUa. 



Pinnigrada. The temporal ridges often meet upon the sagittal suture {exc. 

 Cystophora), but seldom form more than a very slight crest (exc. Otaria). The 

 malar is frequently joined by the zygoma to bound the orbit posteriorly (exc. 

 Tricha3cus). The Lachrymals are wanting. There are no * bullae ' in Otaria 

 or Trichsecus. The Paroccipitals are generally distinct from the Mastoids : the 

 latter are often largely developed, especially in Trichsecus, in which their great 

 development causes considerable lateral expansion in the hinder part of the skull. 

 The Pterygoids are seldom perforated for the ecto-carotids (exc. Arctocephalus, 

 Otaria, Trichcccus). V er&isieni fontanelles are commonly present in the occipital. 

 The Palate has commonly a semi- elliptic botmdary posteriorly, but in Otaria it is 

 truncate, and in Cystophora proboscidea the posterior borders of the palatine 

 bones present three notches. The boundary of the jaw extends from below the 

 condyle forward, and rarely developes an angle. 



The Vertehral Column is modified in relation to tlie medium in 

 whicli the species live, degree of carnivority, and mode of motion. 

 In no Sectorialia do Cervical yertebrae articulate by ball-and-socket 

 joints ; the seventh C. v. always has the transverse processes imper- 

 forate, consisting only of diapophyses. The Dorso-Limilar scries 

 numbers twenty vertebrce constantly ; the proportion of 'Dorsal' to 

 * Lumbar ' varies with the agility of the species, the most agile 

 Digitigrada having two or three less of free elongated pleurapophyses 

 than the stiffer trunked Plantigrada and Pinnigrada. A similar 

 variation is to be found in the development of Anapophyses, which 

 increase in size directly as the lithe action of the species tends to 

 dislocation of the vertebrae. Lastly, the Anticlinal vertebra is more 

 distinctly marked in direct correlation with the development of the 

 anapophyses. In the Planti-, Semi-planti-, and Digiti-grada, the 

 Pro-zygapophysis of one Lumbar vertebra is received into the inter- 

 space between the post-zygapophysis and the anapophysis of the 

 antecedent vertebra ; thus inducing an interlocking articulation. 



Digitigrada. In Leo the spine of the axis has great height, length, and posterior 

 breadth, arching forward and backward, and overlapping the third Y. of which the 

 spine is obsolete : the spine of the fourth V. is short and vertical, indicating the 

 centre of motion of the neck. The anterior dorsal spines are lofty and strong for 

 the origin of muscles implanted in the ridged and pitted back part of the skull. 

 The Lumbar diapopJtyses are long and antroverted. The Sacrum of Canis rufus 

 (fox) is remarkable for its sudden diminution of size, as compared with the lumbar 

 vertebrae. Certain Viverridce, e.g. Paradoxiu'us (Palm-cat) have the tail organ- 

 ised for prehension. 



Semi- Plantigrada. In Lutra the spines of the three sacral vertebroe have 

 coalesced to form a vertical crista, and the tail is longer and stronger than in the 

 terrestrial Mustelidoc. 



Plantigruda. The number of true vertebrae is twenty-seven as a rule, and 



