CHAPTER I. The Biology of the Crocodilia

THE BIOLOGY OF THE CROCODILIA

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 | |