TEETH AND BRAIN. 473 



ment causes the partial rotation of the inferior maxilla or lower jaw, and this 

 rotation throws the fang into an erect position. The act of striking causes a 

 muscle to contract over the poison sac and the fluid is forced into the wound 

 through the grooved fang. When the fang is withdrawn the mouth shuts and 

 the parts return to their first position, and the fang lies upon the roof of the 

 mouth in a fold of mucous membrane. We certainly cannot award to this class 

 (ophidian reptiles) a very high order of intelligence. 



The alligator or American crocodile is a familiar reptile. It is a native of 

 the Lower Mississippi, and its characteristics are well known. The teeth are aH 

 the same shape and the same number from birth to death, each tooth being re- 

 placed by its successor growing inside the old one and causing its absoption, and 

 eventually taking its place without making a new socket. The teeth are all 

 pointed, far apart, and firmly planted in the socket. The alligator's brain is non- 

 convoluted, perfectly smooth and one ganglion behind the other. In a head three 

 feet long the brain is the size of the thumb. Notice three points here. The 

 small size of brain, the smoothness of lobes, and the teeth being the same shape 

 and nearly so in size. As regards birds, there is only one authentic specimen 

 found with teeth. That was found by the late Professor Mudge, of Kansas, in the 

 cretaceous deposits of Colorado, Niobrara group. Its beak is about seven and 

 one half inches long by one and a quarter broad. The teeth are arranged in a 

 straight line, and about twenty one in each ramus of the lower jaw, and there 

 appears to be the same number in the upper jaw. This was supposed to be an 

 aquatic bird and used its recurved teeth for securing fish. This fossil is in the 

 possession of Professor Marsh. This bird does not bear upon our subj ect only so far 

 as birds are the connecting link between the reptilian and mammalian classes. 



In the elephant we find a very small brain compared to its size, it being one of 

 the largest existing mammals. The average weight of the brain is from eight to ten 

 pounds. This animal gets its intelligent look from its large frontal sinuses, while in 

 reality the animal is not as intelligent as its looks would indicate. The teeth are 

 formed for a herbivorous diet. The molars, six in number, grow from above 

 downward and outward in continuous plates of enamel, separated by dentine, 

 and surrounded by cementum. The first, or "baby molar, being the smallest, and 

 the last one fifteen inches long. Only one part of the molar is used at a time. 

 The tusks correspond to the incisor teeth. Neither is the size of the brain in 

 proportion to the size of the body, nor its position, nor do the teeth of the ele- 

 phant indicate a high order of intelligence. We will pass by the rodentia or 

 gnawing tribe, comprising the mouse, beaver, squirrel, rabbit, etc., and come di- 

 rectly to the carnivora, of which the tiger is a typical member. We first notice 

 the immense size of the canines, also the spaces between the front teeth for the 

 reception of the lower teeth when the jaws are closed. The molars are made for 

 crushing, yet we can see a gradual approximation to the human molar; the sur- 

 face is not flat like the elephant's nor surmounted with cusps like the human's 

 molar. The facial angle is greater in the tiger than in the preceding animal. 

 The brain is small, sets far back in the head, and the cerebellum is partially cov- 



