Classification
As in most groups of animals, there is considerable difference of opinion as to the proper classification of the Crocodilia.
One of the older textbooks (Claus and Sedgwick) divides the order Crocodilia into three sub-orders: the Teleosauria, Steneosauria, and Procœlia, the last only being represented by living forms. The Procœlia or Crocodilia proper are divided into three families,—the Crocodilidæ, the Alligatoridæ (including the caiman as well as the alligator), and the Gavialidæ.
This division into families seems to be based mainly on the shape of the head, or, at any rate, it throws those forms together that have heads of the same outline.
It is this outline of the head that Ditmars (Reptiles of the World) uses in classifying the Crocodilia, which, he says, are all included in the single family—Crocodilidæ. The following list, taken from his Reptiles of the World (pp. 68-69), will give a clear idea of the number, distribution, and maximum size of the members of the order Crocodilia. More will be said of some of the members of this list later.
| Habitat | Max. Size | |
|---|---|---|
| A. Snout extremely long and slender, extending from the head like the handle of a frying pan | ||
| Gavialis gangeticus, Indian Gavial | Northern India | 30 ft. |
| Tomistoma schlegeli, Malayan Gavial | Borneo and Sumatra | 15 ft. |
| B. Snout very sharp and slender; of triangular outline | ||
| Crocodilus cataphractus, Sharp-nosed Crocodile | W. Africa | 12 ft. |
| Crocodilus johnstoni, Australian Crocodile | Australia | 6-8 ft. |
| Crocodilus intermedius, Orinoco Crocodile | Venezuela | 12 ft. |
| C. Snout moderately sharp; outline distinctly triangular | ||
| Crocodilus americanus, American Crocodile | Fla.; Mexico; Central and S. America | 14 ft. |
| Crocodilus siamensis, Siamese Crocodile | Siam; Java | 7 ft. |
| Crocodilus niloticus, Nile Crocodile | Africa generally | 16 ft. |
| Crocodilus porosus, Salt-water Crocodile | India and Malasia | 20 ft. |
| D. Snout more oval; bluntly triangular | ||
| Crocodilus robustus, Madagascar Crocodile | Madagascar | 30 ft. |
| Crocodilus rhombiferus, Cuban Crocodile | Cuba only | 7 ft. |
| Crocodilus moreletti, Guatemala Crocodile | Guatemala; Honduras | 7 ft. |
| E. Snout short and broad; conformation barely suggesting a triangular outline | ||
| Crocodilus palustris, Swamp Crocodile | India and Malasia | 12 ft. |
| Osteolæmus tetrapis, Broad-nosed Crocodile | W. Africa | 6 ft. |
| D′. Outline of head similar to that of Section D | ||
| Caiman trigonotus, Rough-backed Caiman | Upper Amazon | 6 ft. |
| Caiman sclerops, Spectacled Caiman | Central and S. America | 7-8 ft. |
| Caiman palpebrosus, Banded Caiman | Tropical South America | 7-8 ft. |
| F. Snout very broad; bluntly rounded at tip | ||
| Caiman latirostris,[1] Round-nosed Caiman | Tropical South America | 7-8 ft. |
| Caiman niger,[2] Black Caiman | Tropical South America | 20 ft. |
| Alligator mississippiensis, American Alligator | Southeastern United States | 16 ft. |
| Alligator sinensis, Chinese Alligator | China | 6 ft. |
[1] These species are exceptions in their genus. The snout is blunt like that of the genus Alligator.
[2] Alleged to grow to this size by competent observers.
Gadow in the Cambridge Natural History (p. 450) agrees with Boulanger in believing that the recent Crocodilia cannot be separated into different families, yet he describes seven families of Crocodilia, two of which, the Gavialidæ and Crocodilidæ, include the living members of the order; the former includes the gavials, of course, and the latter the crocodiles, alligators, and caimans.
Though “doctors disagree” thus in regard to the scientific classification of this small group of animals, this fact does not in the least diminish the intense interest in the individual members of the order.