Numbers 2:18

On the west side [shall be] the standard of the camp of Ephraim, according to their armies,.... It was in the rear or behind, consisting of his tribe, and of the tribes of Manasseh and Benjamin, divided into several companies, and extended four miles, as the above Targum. The Jewish writers say l, that Joseph's stone is the onyx or sardonyx, and his flag was coloured very black, and on it were figured for the two princes, Ephraim and Manasseh, Egypt, because they were born in Egypt; and upon the flag of Ephraim was figured an ox, because of what is said in Deuteronomy 33:17; and on the flag of the tribe of Manasseh was figured an unicorn, because of what is said in the same place. Benjamin's stone was the jasper, and his flag was coloured like to twelve colours, and on it was figured a wolf, because of what is said

Genesis 49:27;

and the captain of the sons of Ephraim [shall be] Elishama the son of Ammihud; of whom see Numbers 1:10.

l Bemidbar Rabba, ut supra. (sect. 2. fol. 178. 2.)