There is a something about the second week that I just adore

All rodents with a mouselike or ratlike body, regardless of body size or diagnostic traits, were described as species of Mus between 1758 and the late 1800s. Subsequent study shifted most of those species into many different groups, leaving Mus as a smaller, clearly defined genus with a particular combination of traits. Within the genus there are four distinctive groups: spiny mice (subgenus Pyromys), shrew-mice (subgenus Coelomys), rice field mice and the house mouse (subgenus Mus), and African mice (subgenus Nannomys).