naturalis_ of Pliny, in the medieval encyclopedias, and in the _Physiologus_, a collection of animal lore widely read in the Middle Ages. Further detail regarding the local features of Mesopotamia and Armenia was learned from the expedition of Cyrus and preserved for the future in Xenophon’s _Anabasis_. But the events which did most to expand the regional knowledge of the ancients were those connected with Alexander’s conquests and with the reigns of his successors. Alexander’s march in itself opened to Greek eyes wide territories that had been unknown before; it brought Greek armies and, after them, Greek merchants into the innermost heart of Asia; it established direct connections with India; rumors reached the companions of Alexander of an enormous island of Taprobane in the Southern Ocean, an island which we now recognize to be Ceylon. With the voyage of Nearchus came a better understanding of the Indian seas; and subsequently under Seleucus I (Nicator), Megasthenes, who was sent as ambassador to the court of an Indian potentate on the Ganges, gave a detailed description of the tribes and products of Hindustan, more extensive notes on Taprobane, and—unfortunately—a repetition of the fabulous legends of Ctesias. Patroclus, in command of the easternmost provinces of the kingdom of Antiochus I, provided some valuable statistical and geographical facts about the peoples of the Caspian region, although he was quoted as an authority for the belief that the Caspian communicates with the outer ocean and that it is an easy matter to sail thence to India. GEOGRAPHY AT ALEXANDRIA In addition to the reports of travelers and eyewitnesses, the establishment of Greek control over Egypt and the greater part of southwestern Asia led to a scientific awakening that centered in Alexandria. One of the greatest triumphs of Hellenistic science was the geographical and astronomical school that flourished at Alexandria under the Ptolemies. Eratosthenes and Hipparchus were undoubtedly the most famous representatives of this school, and in them we see the culmination of Greek scientific geography; for their work, all things considered, surpassed that of Claudius Ptolemy, and the work of no other man approached it. Though Eratosthenes’ researches were significant mainly in the field of mathematical geography, he made use of much of the regional knowledge which was available in the library at Alexandria and which he could gain from enterprising Greek traders, administrators, and soldiers who had actually visited the countries with which he deals in his treatises.