The Burgess Animal Book For Children in "Mice With Pockets, And Others"

In each cheek is a pocket opening from the outside, and these pockets are lined with hair.
He is called Silky Pocket Mouse because of the fineness and softness of his coat. He has some larger cousins, one of them being a little bigger than Nibbler the House Mouse. Neighbors and close relatives are the Spiny Pocket Mice."

"Do they have spines like Prickly Porky?"