According to Aristobulus, none of the sea fish ascend the Nile from the sea, except the shad,[385] the grey mullet,[386] and dolphin, on account of the crocodiles; but great numbers ascend the Indus. Small craw-fish[387] go up as far as the mountains,[388] and the larger as far as the confluence of the Indus and the Acesines. So much then on the subject of the wild animals of India. We shall return to Megasthenes, and resume our account where we digressed. 46. After the hunters and the shepherds, follows the fourth caste, which consists, he says, of those who work at trades, retail wares, and who are employed in bodily labour. Some of these pay taxes, and perform certain stated services. But the armour-makers and ship-builders receive wages and provisions from the king, for whom only they work. The general-in-chief furnishes the soldiers with arms, and the admiral lets out ships for hire to those who undertake voyages and traffic as merchants. 47. The fifth caste consists of fighting men, who pass the time not employed in the field in idleness and drinking, and are maintained at the charge of the king. They are ready whenever they are wanted to march on an expedition, for they bring nothing of their own with them, except their bodies. 48. The sixth caste is that of the Ephori, or inspectors. They are intrusted with the superintendence of all that is going on, and it is their duty to report privately to the king. The city inspectors employ as their coadjutors the city courtesans; and the inspectors of the camp, the women who follow it. The best and the most faithful persons are appointed to the office of inspector. 49. The seventh caste consists of counsellors and assessors of the king. To these persons belong the offices of state, tribunals of justice, and the whole administration of affairs. It is not permitted to contract marriage with a person of another caste, nor to change from one profession or trade to another, nor for the same person to undertake several, except he is of the caste of philosophers, when permission is given, on account of his superior qualifications. 50. Of the magistrates, some have the charge of the market, others of the city, others of the soldiery. Some have the care of the rivers, measure the land, as in Egypt, and inspect the closed reservoirs, from which water is distributed by canals, so that all may have an equal use of it. These persons have charge also of the hunters, and have the power of rewarding or punishing those who merit either. They collect the taxes, and superintend the occupations connected with land, as wood-cutters, carpenters, workers in brass, and miners. They [CAS. 708] superintend the public roads, and place a pillar at every ten stadia, to indicate the by-ways and distances.