Phage TP50 resembles phage SP50 ofB.subtilisand phage No. 1 ofB.mycoides. Phage PBC1 has a long tail fiber like flagella-specific phages and resemblesB.pumilusphage PBP1. The latter was reexamined but has different dimensions. Heads of phages TP50 and PBP1 are icosahedral. Staining with uranyl acetate causes shrinkage of phage heads. Lysates ofB.cereuscontain cubic, round, or filamentous particles not previously described.