Who is Abu Zinad and Al-Araj in Imam Malik's Muwatta?

In a few narrations in Imam Malik's muwatta, a sanad from Malik to Abu Hurayra, through Abu Zinad and al-Araj, is present. An example is hadith 66 in book 2: > وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ **أَبِي الزِّنَادِ**، عَنِ **الأَعْرَجِ**، عَنْ أَبِي هُرَيْرَةَ، أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ ‏ "‏ إِذَا شَرِبَ الْكَلْبُ فِي إِنَاءِ أَحَدِكُمْ فَلْيَغْسِلْهُ سَبْعَ مَرَّاتٍ ‏"‏ ‏.‏ Which people exactly are referred to by the names الزِّنَادِ and لأَعْرَجِ? Thanks, Umar