As she looked at all of the vials in the box, she noticed a drawer that contained even more. Pulling it out, she found over twice as many vials contained within. In fact, unless her eyes were playing tricks, it seemed that the drawer itself was awful long to actually fit within the box. She closed it, finding it was perfectly flush with the box's edges. She guessed it was either her imagination, or there was some kind of magic on the box akin to Mary Poppins' handbag.
Opening it again, she saw the vials were divided into several sections. Most of them had labels according to species or classification, but one section was marked "Selective Transformation."
Looking over these vials, she saw words like Hooves, Claws, Horns, Extra Arms, Extra Legs, Tails, Wings, Furs and more. Fine print underneath the section heading read "Use these vials to gain a specific animal characteristic without sacrificing the rest of your form."
So Jess had the option of only modifying one part of Mary's body. But which part, out of all the possibilities in the animal kingdom, would she choose?