The most valuable of the fish belonging to the Persian seas and rivers were the pearl oyster of the Gulf, and the murex of the Mediterranean, which furnished the famous purple dye of Tyre.  After these may be placed the sturgeon and sterlet of the Caspian, the silurus of the Sea of Aral, the Aleppo eel, and the palla, a small but excellent fish, which is captured in the Indus during the flood season.  The Indian Ocean and the Persian Gulf, as we have seen, were visited by whales; dolphins, porpoises, cod, and mullet abounded in the same seas; the large rivers generally contained barbel and carp; while some of them, together with many of the smaller streams, supplied trout of a good flavor.  The Nile had some curious fish peculiar to itself, as the oxyrinchus, the lepidotus, the Perca Nilotica, the Silurus Schilbe Niloticus, the Silurus carmuth and others.  Great numbers of fish, mostly of the same species with those of the Nile, were also furnished by the Lake Moeris; and from these a considerable revenue was derived by the Great Kings.

Among the more remarkable of the reptiles which the Empire comprised within its limits may be noticed—­besides the great saurians already mentioned among the larger animals—­the Nile and Euphrates turtles (Trionyx Egypticus and Trionyx Euphraticus), iguanas (Stellio vulgaris and Stellio spinipes), geckos, especially the Egyptian house gecko (O. lobatus), snakes, such as the asp (Coluber haje) and the horned snake (Coluber cerastes), and the chameleon.  The Egyptian turtle is a large species, sometimes exceeding three feet in length.  It is said to feed on the young of the crocodile.  Both it and the Euphrates turtle are of the soft kind, i.e., of the kind which has not the shell complete, but unites the upper and under portions by a coriaceous membrane.  The turtle of the Euphrates is of moderate size, not exceeding a a length of two feet.  It lives in the river, and on warm days suns itself on the sandbanks with which the stream abounds.  It is active, strong, violent, and passionate.  When laid on its back it easily recovers itself.  If provoked, it will snap at sticks and other objects, and endeavor to tear them to pieces.  It is of an olive-green color, with large irregular greenish black spots.

Iguanas are found in Egypt, in Syria, and elsewhere.  The most common kind (Stellio vulgaris) does not exceed a foot in length, and is of an olive color, shaded with black.  It is persecuted and killed by the Mahometans, because they regard its favorite attitude as a derisive imitation of their own attitude of prayer.  There is another species, also Egyptian, which is of a much larger size, and of a grass-green color.  This is called Stellio spinipes:  it has a length of from two to three feet.