April; or rather, I will, for convenience, restrict myseltMo the two 

 largest of these, as affording fairer results. They were from ten to 

 eleven feet long, and from three to four feet in circumference, in the 

 thickest part of the body. They corresponded with others, some larger 

 and some smaller, which I have casually examined. The two I allude 

 to, were examined several times daily, with much and prolonged atten- 

 tion. They were kept in cages or boxes, the bottoms and a portion of 

 the sides of which were watertight, the residue being lattice work, or 

 rather bars, which admitted wind, rain, and sun. The animals were 

 sometimes kept partly immersed, and sometimes quite dry, during the 

 periods of examination. During many of the observations on temperature 

 of the gullet, aud on the digestion of food, the mouth was opened, and 

 was retained so by strong levers, in order to facilitate the experiments, 

 and to prevent the crushing of the arm, &c. 



The upper jaw is wider than the under, v/hich it overlaps. The latter 

 lias forty teeth, none of which are grinders, as asserted by Professor 

 Owen — none are cutting or incisor teeth, as they are described to be by 

 Goldsmith. The teeth of the upper jaw are similar in number and 

 structure. 



The Cuvierian classification is based on the teeth, which this author 

 says, " are for the Alligator, thirteen on each side of the upper jaw. 

 The fourth tooth, on each side of the under jaw^, enters a hole in the 

 upper." 



Professor Edwards, of Paris, in his work on Zoology, (p. 367) char- 

 acterises the Nilotic Crocodile by its dental organization, but in the 

 very same page, gives these identical characteristics, by vdiich to dis- 

 tinguish the Alligator. Both are recognised by the fourth tooth, one on 

 each side of the lower jaw, as entering sockets in the upper ; an excellent 

 example of a distinction without a difference, not unlike Shakspeare's 

 two lovers : 



'' Two dSstincts, division none." 



Professor Owen, of London, is quoted in the British and Foreign 

 Medical Review, for January, 1846, as maintaining, in his recent work 

 on Odontography, that "the Crocodile has as many as four generations 

 of molar feeth.^'' Buffon's account of the teeth agrees with Cuvier's. 

 Geoffrey St. Hilaire, naturalist to the Egyptian Expedition, enumerates 

 36 in the upper, and 30 in the lower jav/, all of which, according to his 

 engraving, (pi. 2, croc, vulg.) are long and conical. Now, the facts are 

 these : in both jaws there are 80 teeth, nearlyhalf of these, that is 36 or 

 38, are short blunt teeth, rising but little above the gum, wholly different 

 from grinders — never being worn — occupying the interspaces between 

 the long conical teeth, M'hich latter amount to 42 or 44, and are round, 

 white, polished, tapering, salient, and projc^ct from the gum nearly an 

 inch, usually exceeding a quarter of an inch in diameter. As the lower 

 jaw is less expanded than the upper, its long teeth, 20 to 22 in number, 

 are received, not only within the dental range of the upper jaw, hut Jit 

 into as many holes in the latter. Instead, therefore, of two long teeth 

 fitting into two sockets, there are never less than 20 long teeth fitting into 

 as many sockets in the roof of the mouth — an arrangement which totally 



