INTRODUCTION. 5 



known as " breeds " being, in all probability, due to the pro- 

 longed influence of external circumstances, such as locality, 

 treatment, climate and selection. In the Equidse the stomach 

 is simple and comparatively small. 



ARTIODACTYLA. 



Ruminantia. — The ox, sheep, goat, camel, ?jid llama belong 

 to this section -of ruminating animals, so named from their habit 

 of remasticating their food. They, are all cloven-footed, or 

 have two digits. Very generally the skull of the ruminant is 

 provided with a pair of horns ; and the ox, sheep, and goat are 

 classed as Cavicornia, their horns being hollow, and supported on 

 bony cores. Ruminants are mostly without front teeth in the 

 upper jaw, and their stomach is very large and complex. 



Omnivora. — The pig is classed in this section. Its teeth are 

 of a mixed order, calculated to deal with many kinds of food, 

 hence -the name Omnivora. The canine or eye teeth are very 

 prominent, and in the male they project considerably as "tusks," 

 which in the wilder varieti,es are formidable weapons. The 

 stomach is intermediate in complexity between that of the 

 ruminant and that of the horse. This animal has four digits, 

 two long and two short on each extremity. The nose, or snout, 

 is prominent, and rather cylindrical in form. 



CARNIVORA. 



Ualike any of the above-named animals, the dog and cat are 

 placed in this natural order, an order characterised by large 

 canine teeth, and by there being no lateral or grinding motion 

 between the jaws. The anterior extremity is supplied with ^ve, 

 the posterior with four or five digits, which are terminated by 

 sharp or blunt, retractile or non-retractile claws. The stomach 

 is small, and the intestine comparatively short. 



RODENTIA. 



This natural order, to which the rabbit belongs, although an 

 extensive order, is sufficiently distinguished by the possession of 

 two large chisel-shaped incisor or front teeth, which are found in 

 each jaw, the canine teeth being altogether wanting. 



DOMESTICATED AVES. 



Birds are distinguished from Mammals by their producing 

 their young oviparously, or by hatching the egg outside the body. 



