What is Marco Polo describing here in "The Travels Of Marco Polo", The Venetian?
"Leaving the city of Yachi and traveling ten days into a westerly direction, you reach the Province of Karazan which is also the name of its chief city… Here are seen huge serpents, ten paces in length and ten spans in the girt of the body. At the fore-part, near the head, they have two short legs, having three claws like those of a tiger, with eyes larger than a fourpenny loaf and very glaring. The jaws are wide enough to swallow a man, the teeth are large and sharp and their whole appearance is so formidable, that neither man, nor any kind of animal, can approach them without terror. Others are met with a smaller size, being eight, six or five paces long; and the following method is used for taking them: In the day-time, by reason of the great heat, they lurk in caverns, from whence, at night, they issue to seek their food and whatever beast they meet with and can lay hold of, whether tiger, wolf, or any other, they devour; after which they drag themselves towards some lake, spring of water, or river, in order to drink. By their motion in this way along the shore, and their vast weight, they make a deep impression, as if a heavy beam had been drawn along the sands."
"Those whose employment it is to hunt them observe the track by which they are most frequently accustomed to go, and fix into the ground several pieces of wood, armed with sharp iron spikes, which they cover with the sand in such a manner as not to be perceptible. When therefore the animals make their way towards the places they usually haunt, they are wounded by these instruments and speedily killed. The crows, as soon as they perceive them to be dead, set up their scream; and this serves as a signal to the hunters, who advance to the spot and proceed to separate the skin from the flesh, taking care immediately to secure the gall, which is most highly esteemed in medicine. In cases of the bite of a mad dog, a pennyweight of it, dissolved in wine, is administered. It is also useful in accelerating parturition, when the labour pains of women have come on. A small quantity of it being applied to carbuncles, pustules or other eruptions on the body, they are presently dispersed; and it is efficacious in many other complaints. The flesh of the animal is also sold at a dear rate, being thought to have a higher flavour than other kinds of meat and by all persons it is esteemed a delicacy."