connected with the disappearance of Reptilia, against the attacks of which a better coat of mail may have advantaged the contemporary Mesozoic Crocodilia, it may further be remarked that diminution of weight would favour crocodilian movements in air, and that a loosely jointed armour would less impede the evolutions required to catch a prey on land.
In this relation, also, arising out of the introduction, in Tertiary times, of large many species of warm-blooded mammals frequenting the banks of lakes and rivers tenanted by carnivorous Alligators and Crocodiles, I have been led to ponder upon the well-marked difference in the relative position of the 'palato-nares' (internal or posterior nostrils, figs. 3 & 6 N) which exists between the Secondary and Tertiary Crocodiles.
Figs. 1-3. — Cranium of Crocodilus.
1, Lateral view.
O. Orbits.
T. Temporal apertures.
2. From above.
P. Ptery go-maxillary
apertures. N. Palatal nostril.
3. From below.
V. Venous foramen. E. Eustachian foramen.
The physiologist discerns in the soft palatal and gular structures, concomitant with the backward position and small size of the 'palato-
