1911 Encyclopædia Britannica/Crocodile
CROCODILE, a name for certain reptiles, taken from ancient Gr. κορδύλος, signifying lizard and newt; with reduplication κορκορδύλος, and by metathesis ultimately κροκόδειλος. Herodotus makes mention of them, and tells us that the Egyptian name was champsa. The Arabic term is ledschun. The same root kar leads through something like kar-kar-ta, glakarta (glazard in Breton), to lacerta and to “lizard.” Lacerta in turn has become, in Spanish, lagarto, which, with the article, el lagarto, is the origin of the term “alligator.” This word is, however, artificial, although now widely used; Spanish and Portuguese-speaking people in America universally call the crocodile and the alligator simply lagarto, which is never intended for lizard.
The Crocodilia form a separate order of reptiles with many peculiarities. The premaxillae are short and always enclose the nostrils. The posterior nares or choanae open far behind in the roof of the mouth, in recent forms within the pterygoids. The under jaws are hinged on to the quadrate bones, which extend obliquely backwards, and are immovably wedged in between the squamosal and the lateral occipital wings. The teeth form a complete series in the under jaw, and in the upper jaw on the premaxillary and maxillary bones. They are conical and deeply implanted in separate sockets. They are often shed throughout life, the successors lying on the inner side, and with their caps partly fitting into the wide open roots of the older teeth. Especially in alligators the upper teeth overlap laterally those of the lower jaw, whilst in most crocodiles the overlapping is less marked and the teeth mostly interlock, a feature which increases with the slenderness of the snout. In old specimens some of the longer, lower teeth work their tips into deep pits, and ultimately even perforate the corresponding parts of the upper jaw. The first and second vertebrae each have a pair of long, movable ribs. There is a compound abdominal sternum. The so-called pubic bones are large and movable. There are five fingers and four toes, provided with claws, excepting the outer digits.
The tongue is flat and thick, attached by its whole under surface; its hinder margin is raised into a transverse fold, which, by meeting a similar fold from the palate, can shut off the mouth completely from the wide cavity of the throat. Dorsally the posterior nares open into this cavity. Consequently the beast can lie submerged in the water, with only the nostrils exposed, and with the mouth open, and breathe without water entering the windpipe. Within the glottis is a pair of membranous folds which serve as vocal cords; all the Crocodilia are possessed of a loud, bellowing voice.
The stomach is globular, rather muscular, with a pair of tendinous centres like those of birds; its size is comparatively small, but the digestion is so rapid and powerful that every bone of the creature’s prey is dissolved whilst still being stowed away in the wide and long gullet. The anal opening forms a longitudinal slit; within it, arising from its anterior corner, is the unpaired copulatory organ. The vascular system has attained the highest state of development of all reptiles. The heart is practically quadrilocular, the right and left halves being completely partitioned, except for a small communication, the foramen Panizzae, between the right and left aortae where these cross each other on leaving their respective ventricles. The outer ear lies in a recess which can be closed tightly by a dorsal flap of skin. The power of hearing is acute, and so is the sight, the eyes being protected by upper and lower lids and by a nictitating membrane. The skin of the whole body is scaly, with a hard, horny, waterproof covering of the epidermis, but between these mostly flat scales the skin is soft. The scutes or dermal portions of the scales are more or less ossified, especially on the back, and form the characteristic dermal armour. The skins or “hides” of commerce consist entirely of the tanned cutis minus, the epidermis and the horny coverings of the scutes. All the Crocodilia possess two pairs of musk-glands in the skin; one is situated on the inner side of the lower jaw. The opening of the glands is slit-like and leads into a pocket, which is filled with a smeary, strongly scented matter. The other pair lies just within the lips of the cloacal opening.
Propagation takes place by eggs, which are oval, quite white, with a very hard and strong shell. Their size varies from 2 to 4 in. in length, according to the size of the species and the age of the female. She lays several dozen eggs in a carefully prepared nest. The Nile crocodile makes a hole in white sand, which is then filled up and smoothed over; the mother sleeps upon the nest, and keeps watch over her eggs, and when these are near hatching—after about twelve weeks—she removes the 18 in. or 2 ft. of sand. Other species, especially the alligators, make a very large nest of leaves, twigs and humus, scraping together a mound about a yard high and two or more yards in diameter. The eggs, in several layers, are laid near the top. The adults frequently dig long subterranean passages into the banks of streams, and, during dry seasons, they have been found deep in the hardened mud, whence they emerge with the beginning of the rains. They spend most of their time in the water, but are also very fond of basking in the hot sun on the banks of rivers or in marshes, usually with the head turned towards the water, to which they take on the slightest alarm. They can walk perfectly well, and they do so deliberately with the whole body raised a little above the ground. When their pools dry up, or when in search of new hunting-grounds, they sometimes undertake long wanderings over land. But the water is their true element. They swim rapidly, propelled by the powerful tail and by the mostly webbed limbs, or they submerge themselves, with only the tip of the nose and the eyes showing, or sometimes also the back. They then look like floating logs; and thus they float or gently approach their prey, which consists of anything they can overpower. Many a large mammal coming to drink at its accustomed place is dragged into the water by the lurking monster. Certainly there are occasional man-eaters amongst them, and in some countries they are much feared. As a rule, however, they are so wary and suspicious that they are very difficult to approach, and their haunts are so well stocked with fish and other game that they make off and hide rather than attack a man swimming in their waters. But if a dog is sent in there will be a sudden yelp, the splash from a big tail, and a widening eddy.
Crocodile stories, not all fabulous, are plentiful, and begin with one of the oldest writings in the world, the book of Job. “Canst thou draw leviathan with a hook? or his tongue with a cord which thou lettest down?... Lay thine hand upon him, remember the battle, do no more.” This is a very interesting passage, since it can apply only to a large-sized crocodile. Now nothing is known of the occurrence of such in Arabia, but a few specimens of rather small size seem still to exist in Syria, in the Wadi Zerka, an eastern tributary of the Jordan.
Crocodiles are caught in various ways,—for instance, with two pointed sticks, which are fastened crosswise within the bait, an animal’s entrails, to which is attached a rope. When the creature has swallowed the spiked bait it keeps its jaws so firmly closed that it can be dragged out of the water. A kind of plover, Pluvianus aegyptius, often sits upon basking crocodiles, and, since the latter often rest with gaping mouth, it is possible that these agile birds do pick the reptiles’ teeth in search of parasites. Being a very watchful bird, its cry of warning, when it flies off on the approach of danger, is probably appreciated by the crocodile. But the story of the ichneumon or mongoose is a fable. Although an inveterate destroyer of eggs, this little creature prefers those of birds and the soft-shelled eggs of lizards to the very hard and strong-shelled eggs which are deeply buried in the crocodile’s nest.
Considering the interest which is taken in crocodiles and their allies, on account of their size, their dangerous nature and the sporting trophies which they yield, the following “key,” based upon easily ascertained characters of the skull, is given.
I. Snout very long and slender. The mandibular symphysis extends backwards at least to the fifteenth tooth.
(a) Nasal bones very small, and widely separated from the premaxilla (which encloses the nostrils) by the maxillaries which join each other for a long distance along the dorsal mid-line.... Gavialis gangeticus of India, the “gharial” or fish-eater.
(b) Nasal bones long, so as to be in contact with the premaxilla at the hinder corner of the nostril groove.... Tomistoma schlegeli of Borneo, Malacca and Sumatra.
II. Snout mostly triangular or rounded off. The mandibular symphysis does not reach beyond the eighth tooth.
(a), The fourth mandibular tooth fits into a notch in the upper jaw. Crocodiles.
1. Without a bony nasal septum between the nostrils.... Crocodiles.
2. The nasal bones project through the nasal groove, forming a bony septum. Osteolaemus frontatus s. tetraspis of West Africa.
(b) Fourth mandibular tooth fitting into a pit in the upper jaw. Alligators.
1. Without a bony nasal septum.... Caiman, Central and South America.
2. Nasal bones dividing the nasal groove.... Alligator, America and China.
The genus Cracodilus contains seven species. C. vulgaris or niloticus of most of Africa, is found from the Senegal to Egypt and to Madagascar, reaching a length of 15 ft. It has eighteen or nineteen upper and fifteen lower teeth on each side. C. palustris, the “mugger” or “marsh crocodile” of India and Ceylon, extends westwards into Baluchistan, eastwards into the Malay islands. It has nineteen upper and lower teeth on either side. The scutes on the neck, six in number, are packed closely together, the four biggest forming a square. The length of 12 ft. is a fair size for a large specimen. C. porosus or biporcatus is easily recognised by the prominent longitudinal ridge which extends in front of each eye. Specimens of more than 20 ft. in length are not uncommon, and a monster of 33 ft. is on record. It is essentially an inhabitant of tidal waters and estuaries, and often goes out to sea; hence its wide distribution, from the whole coast of Bengal to southern China, to the northern coasts of Australia and even to the Fiji islands. Australians are in the habit of calling their crocodiles alligators. C. cataphractus is the common crocodile of West Africa, easily recognised by the slender snout which resembles that of the gavial, but the mandibular symphysis does not reach beyond the eighth tooth. C. johnstoni of northern Australia and Queensland is allied to the last species mentioned, with which it agrees by the slender snout. Lastly there are two species of true crocodiles in America, C. intermedius of the Orinoco, allied to the former, and C. americanus or acutus of the West Indies, Mexico, Central America to Venezuela and Ecuador; its characteristic feature is a median ridge or swelling on the snout, which is rather slender.
The above list shows that the usual statement that crocodiles inhabit the Old World and alligators the New World is not strictly true. In the Tertiary epoch alligators, crocodiles and long-snouted gavials existed in Europe. (H. F. G.)