42 Mammalia. Perissodactyla. 



tlie head of the Femur ; the small one is almost obsolete. The Tibia 

 and Filula are distinct throughout their length. 



In the Proboscidia the following characters recall the ' Rodent ' type, viz. : 

 the epencephalic wholly behind the pros- and mes-encephalic cerebral cavities ; 

 the malar bone suspended in the middle of the zygomatic arch ; the pj'cemaxil- 

 laries large and excluding the maxillary from the nasal ; the large alveoli 

 for the single pair of incisors : lastly the spine of the scapula extended into a 

 short pointed acromion and sending down a process. 



YIII. PERISSODACTYLA. 



The Shull. The Nasals expand posteriorly. The slender Fterygoid 

 process has a broad and thick base, and is perforated lengthwise by the 

 ectocarotid artery. The major part of the Posterior Aperture of the 

 Nostrils is bounded by the Palatine bones of which only a small portion 

 enter into the formation of the bony palate ; the Bony Palate termin- 

 ates behind, generally in the neighbourhood of the penultimate Molar 

 tooth. The Post-tympanic process is well developed. The Jaws are 

 long and slender. If the species be horned the Horn is usually single, 

 but if there be two, they are of unequal size, and placed on the 

 median line of the head, one behind the other j each being thus a 

 single or odd horn. 



SoUdungttla. The roof of the orbit is produced outwardly and the osseous 

 framework is completed posteriorly by the junction of the post-orbital with the 

 zygoma. The base of the post-orbital process is perforated for the superorhital 

 foramen. The lachrymal canal begins by a single foramen. The Prccmaxillaries 

 extend to the nasals, which are very long and conspicuous, and shut out the 

 maxillaries from the anterior aperture of the nostrils. The post-tympanic 

 process is separated from the paroccipital process by the intervention of the 

 tuberous mastoid. The tentorium is ossified. 



Multungula. The orbit is incomplete. The superorbital foramen is absent. 

 The lachrymal canal commences by tioo distinct orifices. The prcemaxillariea 

 terminate before reaching the nasals. ^Ylq post-tympanic process either imites 

 with the lower part of the paroccipital, e.g., in Tapir ; or, seems to take the place 

 of the mastoid, e.g. in Ehinoceros. 



The Vertebral Column. In both the Cervical and Dorsal vertebrae 

 the fore part of the centrum is convex, the hind part concave, i.e. the 

 joints of the centra are Opisthoccelian. The Dorso-lumhar vertebrae 

 are never fewer than twenty-two. There are commonly eight pair 

 of Ribs directly joined to the Sternum which consists of seven bones 

 and a xiphoid cartilage. The Sacral vertebrae are frequently five or 

 six in number, but ofthese only two or three articulate with the 

 Ilia. 



