i think he means to do with riding animals, if so this is a large quote from the website.
\'\'Travel
The Slow Way
Long stairs that wind on the walls or corridors dug in the rock connect every adjacent level. Most citizens walk from level to level, even though such a trip is very tiring, especially when going uphill with a load of goods. Because of this, wide landings were built where they can lay down their loads and rest.
The Merchandising Way
Because walking is so slow and cumbersome, an ingenious system of pulleys, wheels, and spider silk ropes was devised. These silk ropes attach to either people or goods and are then lifted up. The winches are privately owned, however, so generally they only belong to the mercantile society, and their use is allowed only after a fee is paid to the society, which varies according to the quality of the winch.
The Elite Way
The fastest way of getting over remarkable distances in a short time is using flying animals: Pterosaurs and Megaras.
Flying Animals
Pterosaurs
The Pterosaurs are reptiles with organs adapted to flight, such as their membranous wings and long tails, which they use as a rudder. The Pterosaurs\' dimensions vary from three to six meters, not including their tails, and their wingspan is directly proportionate to their bodies. From the moment they are born, Pterosaurs begin training to carry a person sitting in a saddle buckled between the animal\'s shoulder blades. Pterosaurs must be at least three years old and fully trained before they can actually carry a person, which makes them precious, coveted, and very expensive to keep. Only extremely wealthy people can afford these lizards, but no matter how wealthy a family is they may only legally own a single Pterosaur. The law forbids owning more than one of these animals in order to avoid dangerously crowding the limited air space.
Megaras
The second flying animal is the Megaras, which is similar to a giant bat. Scientists believe the Crystal has genetically mutated the Megaras, since they reproduce only in Yliakum. These bat-like creatures are not as docile as the Pterosaurs, but they are stronger and more efficient, making them perfect to carry heavy but not too delicate loads, such as food and building materials. As with the Pterosaurs, each mercantile society is allowed to own only one Megaras.
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