ANATOMY OF THE KANGAROOS. 



193 



TEETH OF THE GREAT KANGAROO. 

 (A) Upper and Lower Jaw; (B) Upper Molar ; (c) Lower Molar. 



are at the side of the end of the muzzle, and are slit-like and oblique, and there are bristly "smellers" 

 to the fleshy lips and chin. A slender tongue is sometimes seen for an instant whilst the Kangaroo 

 is feeding, and if the bones of the jaws be examined, the angle, or lower part of the back of the lower 

 jaw, will be found to be turned inwards. 



The long jaws have not very many teeth, and there are two large lower front ones, or lower 

 incisors, which project in a line with the lower jaw ; they are horizontal and more or less pointed, but 

 have an outer and inner cutting edge. The upper incisors, six in number, or three on each side of 

 the middle line, are placed on the pre-maxillary bone, and they work up and down. They are 

 broad and have the cutting edge below, and the outer one, on each side, is broad, grooved, and 

 complicated by one or two folds of its enamel, which are continued from the outer side of the tooth 

 obliquely forward and inward. There is a space or diastema behind the incisors. There are four pre- 

 molars, one on each side of both jaws, and then follow four molar teeth above and below and on both 

 sides of the mouth. The dental formula is thus Incisors, jEf ; premolars, J-Ej ; molars, |_^ = 28. 



There are no canine teeth in the 



\ 



A 



adults, but their germs may be 



found in the very young Kangaroos. 



As the Kangaroo is a vegetable 



feeder, and delights in grass, leaves, 



and herbs, its teeth are eminently 



of a non-carnivorous kind. It may 



be remarked that when the mouth 



is closed, the cutting edges of the 



upper incisors come against the 



outer cutting edge of the long front 



teeth of the lower jaw. The true 



molars increase in size from front 



backwards ; and the crown of each 



molar is squarish, but is longer than broad, and it has two principal cross ridges, which, when not 



worn, are tall, and have sharp edges. Besides these, there are two other transverse ridges which are 



smaller and not so tall. One of these is on the front part of the tooth, and the other on the hinder (in 



the upper molars only). Then there is a long ridge which connects the cross ones. They are all 



covered with enamel. When the tooth is worn, we find it presenting, according to Mr. Waterhouse,* 



two powerful loops or folds. On comparing these teeth with those of the herbivorous mammalia 



already noticed, a remarkable difference will be seen. 



The hinder extremities consist of a nearly straight, long, cylindrical bone, the femur, which 

 has a hemispherical joint head, and a large trochanter, which reaches above the joint ; of two 

 leg bones the tibia, which is prismatic above and cylindrical below, but with only a slight 

 inner ankle projection, and the fibula, which is distinct but thinned and concave in its lower half, 

 where it is close and attached to the other bone, and forms the outer ankle projection. To these are 

 added the bones of the ankle-joint and the clawed toes. The Kangaroo being a great jumper, and 

 having a great tendon, the analogue of the tendo achillis of man, has a powerful projecting process of the 

 hinder ankle bone for its attachment. But the great length of the foot is produced by the size of the 

 fourth and fifth or two outer toes, and especially of the fourth, which often reaches a foot in length, 

 including the metatarsal bone behind, and the pointed claw in front. The great claw looks like a long 

 hoof, is three-sided and sharp-pointed like a bayonet, and with it the animal stabs and rips open the 

 body of its opponent.t The outer claw is very small, and there is no great toe (or first), but the second 

 and third are long and slender, and are united in a common skin, so as to look like a single toe with 

 a double nail, the hair coming to the roots of it. The long narrow foot is nearly as long as 

 the leg bones, and is admirably adapted for jumping forwards, as well as sideways, and for sup- 

 porting, when the legs are widely separated, the weight of the erect body. The body in that 



* "Water-house's " Natural History of the Mammalia," order Marsupiata, from which much of this description of the 

 order has been taken. 



t R. Owen, " Marsupialia ;" " Todd's Cyclopaedia of Anatomy and Physiology." 



