[Trouvere]

Here is some info I found:
There were 24 such courses and that of Abijah was the eighth (1Ch_24:10; 2Ch_8:14). Only four of these courses (Jedaiah, Immer, Pashur, Harim) returned from Babylon, but these four were divided into twenty-four with the old names. Each of these courses did duty for eight days, sabbath to sabbath, twice a year. On sabbaths the whole course did duty. At the feast of tabernacles all twenty-four courses were present.