hda is a drive, not a partition. The partitions on drive hda are called hda1, hda2, hda3, .... and so on.

By the way, USB drives will most likely be drives calles sda (or sdb, sdc, ...) , not hda! With hda you will adress an internal IDE drive. Take care of your data!
(Thus, partitions on sda will be called sda1, sda2, .....)