This may be accounted for from the apparent fact, that the interior sculpture was executed _after_ that on the outward walls; for it appears to be far more beautiful and elaborate, and thence more time would be required for its completion, and as a consequence, it could only be finished at a later date; added to this a greater protection from the weather is given to the _inside_ of quadrangular walls than on the outside, and that without any reference to roofs or coverings: for a strong wind striking, for instance, an easterly wall on the outside, the force of the wind is destroyed, and consequently reaches the opposite wall _in the area_ with a greatly diminished power. The same argument would apply to the wind from any quarter, blowing upon unroofed quadrangular structures, and this these builders seem to have completely understood by making the Sculpture more refined and delicate upon the inside. "On one side the combination [of the Sculpture] was in the form of diamonds, simple, chaste, and tasteful: and at the head of the courtyard _two gigantic serpents_ (with their heads broken and fallen) were winding from opposite directions along the whole façade"--[_i. e._ one thousand feet]. It will be remembered that the Chief Altar at Copan has sculptured on it _two serpents_: in the Analogies we shall endeavour to read these wily hieroglyphics. "In front and on a line with the door of the preceding edifice, is another building on a lower foundation of the same general character, called _Casa de Tortugas_, from the sculptured _turtles_ over the doorway." That the reader may not be misled, these "turtles" are not as defined in Scripture (_i. e._ young doves), but the _tortoise_, the well-known shellfish; and in the splendid illustrations of these Ruins in Waldeck's work (folio, 1838) the _tortoise_ is distinctly given, and without doubt is so meant by Mr. Stephens. There are _four of them_ in a group, their heads approaching to a centre, _each tortoise_ is in a square, and in the two external angles of each square is an _Egg_. The _tortoise_ and _the egg_, are both National emblems, and the Nation claiming them will be proved in the Analogies.