I distinguish two genera in this family, Rhynchosuchus and Gavialis.
Genus 6. Rhynchosuchus.
There are twenty teeth above, and eighteen or nineteen below, on each side; the mandibular symphysis extends to the fifteenth tooth. The posterior teeth of the upper jaw, and almost all those of the lower jaw, are received into interdental pits; the orbital margins are not raised; and the premaxillæ are hardly at all expanded. The premaxillo-maxillary suture does not reach the third tooth behind the notch.
I propose the name Rhynchosuchus to indicate that generic type which is at present represented by the solitary species called by Müller and Schlegel Crocodilus (Gavialis) Schlegelii, and admirably described and figured by them in their essay, 'Over de Krokodilen van der Indischen Archipel,' in the 'Verhandelingen over de natuurlijke Gesch. der Nederl. overzee. Bezittingen,' 1839-1844. Under the title Crocodilus (Gavialis) Schlegelii (p. 18), they say—"The Gavial from Borneo, when compared with the Indian one, is principally distinguished by the following characters:—
"1. By its stronger form and better developed limbs.
2. By its much less slender head and snout, which last does not narrow so suddenly in front of the eyes as in G. Gangeticus.
3. By the smaller number of teeth, of which there are twenty above and eighteen below on each side, while G. Gangeticus has 28/26 or 27/25; furthermore, the teeth are stouter, less curved, and less sharp, and are disposed more perpendicularly, and the ninth tooth of the upper jaw (reckoning from the front) is considerably larger and stronger than the others; whence it follows that, just as in the true Crocodiles, the snout at the level of this tooth exhibits a lateral projection.
4. By the shorter symphysis of the under jaw.
5. By the absence of the swollen nasal prominence (neusklep), which characterizes the Gangetic Gavial.
6. By the less expanded form of the tabular upper surface of the hinder part of the skull.