271 



The food, mixed with saliva, but not masticated, passes down 

 the gullet or oesophagus into the paunch. Afterwards the softened 

 food, the "cud," is regurgitated and thoroughly chewed; and, in a 

 semi-fluid state, it is again swallowed. It passes down a special 

 groove or gutter of the gullet wall, which gutter is continued, away 

 from the paunch, and along the upper part of the reticulum, to the 

 manyplies. The food is filtered in the manyplies and then passed 

 on into the abomasum, the stomach proper. 



See Classification, page 263. 



State the Principal Distinguishing Characters of the Perissodactyla^ 



An odd number of digits (odd-toed), which tends to be reduced ; 

 third digit of manus and pes is larger than the others ; second and 

 fourth digits (Rhinoceros) and also the fifth (Tapir) may be present ; 

 first digit is always absent. Astragalus pulley-like (for articulation 

 with tibia), and its distal surface is articulated with navicular and a 

 part of the cuboid. Femur has a third trochanter. Horns, when 

 present (as, e.g., Rhinoceros), are epidermal growths (without bony 

 cores), and are median. Stomach simple ; caecum large. Teats 

 inguinal, i.e., in the groin. Placenta non-deciduate. 



Describe the Teeth and Limbs of the Horse. 



Dentition ; orflff, as the small first premolar soon falls 



<i>J.OO 



out. The canines are generally absent in the mare. There is a 

 considerable gap between the front and back teeth. The incisor." 

 are chisel-shaped, with a deep pit on the crown; the grinders are 

 modifications of the lophodont type (see page 251), they have 

 elongated blunt cusps, and are hypsodont (i.e., having long crowns). 

 The upper molars have six cusps, and the intermediate two are 

 crescentic; the lower molars have four cusps, the intermediate two 

 being absent. When the tubercles become worn dowa, the crown 

 shows folded double laminae or ridges of enamel embedded in the 

 cement. 



Fore-limb. Humerus with two trochanters. Ulna (with olecranon 

 process) fused with radius. Carpus (" knee ") consists of seven 

 bones (trapezium being absent), arranged in two rows of three, with 

 the pisiform projecting behind from the upper row. The horse 

 walks on the nails (hoofs) of its third or middle digits, the only 

 functional ones. Attached to the sides of the long metacarpal 

 (cannon bone) are the splint-like rudiments of the second and fourth 

 digits. The first phalanx is the pastern, the second is the coronet- 

 bone, and the third is the coffin-bone, within the hoof. 



Hind-limb. Femur has a trochanter major and a lower third 

 trochanter. Tibia ankylosed with thin fibula. Between femur and 

 tibia is the stifle-joint, in front of which is the patella. Tarsus 

 (hock) consists of six bones. The metatarsal and phalanges are the 



