Here's a general description of a jerboa:
* Size: They range in size from a few inches to about 8 inches long, excluding the tail.
* Body: Slender, with long hind legs and a short, dense body.
* Tail: Long and bushy, often with a black tuft at the tip. It acts as a counterbalance during hopping.
* Head: Small, with large eyes and prominent ears.
* Fur: Usually a sandy or pale brown, providing excellent camouflage in their desert habitats.
Other features:
* Hind Legs: Their powerful hind legs are adapted for hopping, with long, strong feet and toes. The front legs are much smaller and used for grooming and holding food.
* Eyes: Their large eyes are adapted for nocturnal life, allowing them to see in low light conditions.
* Ears: Large ears help them detect predators and navigate.
If you have a specific type of "hopping mouse" in mind, please provide more details and I'll try to be more specific.