I4 CROCODILES. 



clavicle ; the latter being the median bar seen in the lower figure of the illustration 

 on p. 10. A further peculiarity is the presence of seven or eight pairs of abdominal 

 ribs in the wall of the abdomen, which have no connection with the proper ribs, 

 and have their angle of union directed forwards. 1 As regards the soft parts, the 

 heart differs from that of all other living Reptiles in having four complete chambers, 

 so that the fresh and impure blood can only mingle by means of a communication 

 between the great vessels externally to the heart ; while there is also an incomplete 

 midriff dividing the chest from the abdomen. 



In addition to the preceding characters, which are common to all members of 

 the order, there are certain others found only in the existing forms and some 

 of their nearest extinct allies. One of the most remarkable of these peculiarities 

 is the extremely backward position of the aperture of the internal nostrils, which 

 in the dried skull, as shown on p. 2, is situated close up to the occiput, this being- 

 due to the development of special plates by the bones of the palate, which grow 

 beneath the nasal passage, so as to form a floor to it, and thus completely cut it 

 off from the cavity of the mouth. As the summit of the windpipe is continued 

 upwards into this posterior aperture of the nostrils, crocodiles are enabled to 

 breathe while their mouths are wide open and filled with water. Another dis- 

 tinctive feature of the group, also shown in the figure just referred to, is that the 

 socket for the eye communicates freely behind with the lower temporal fossa. 

 Then, again, all existing members of the order are characterised by the bodies of 

 the vertebrae having the ball behind and the cup in front ; while the ribs of the 

 chest are provided with hook-like or uncinate processes resembling those of birds. 

 In the region of the neck the ribs present the peculiarity of having backwardly 

 projecting and overlapping processes, which effectually prevent these animals from 

 turning their heads to one side. 



Crocodiles are denizens of the tropical and subtropical regions of 

 Habits 



the globe, and are found in such latitudes wherever there are rivers 



or fresh- water lakes of sufficient size for their mode of life ; while one of the 



Indian species habitually resorts to the sea-coast, where it has been seen floating at 



a considerable distance from the land. All of them are excellent swimmers, and 



are mainly propelled when in the water by the aid of their powerful tails ; the 



limbs being chiefly used when walking at the bottom of the water, or on the shore. 



When in repose, crocodiles lie like logs either in the water or on the banks of the 



lakes or rivers they inhabit ; but when in pursuit of their prey in the water they 



move with great speed, while they are also active on land. The young are, 



however, decidedly nimbler in their movements than are the adults. Exclusively 



carnivorous in the diet, some members of the order feed solely upon fish ; while 



others, in addition to fish, prey upon the flesh of all animals that come in their 



way. Adult crocodiles, writes Dr. Giinther, " attack every large animal which 



accidentally approaches them, and in overpowering it the whole of their powerful 



organisation is called into requisition. Seizing the victim between their capacious 



jaws, and fastening their long, pointed, conical teeth into its flesh, they draw it, 



in one moment, by their weight and with a stroke of the tail, below the water and 



drown it. Their gullet is, however, much too narrow to allow of the passage of 



1 These abdominal ribs, connected together by the ligament, are shown in the figure above referred lo. 



