On page 202, when the group is with Stonehead's family, it says "After supper, Dandin sang and played his harolina, an impromtu song." A few paragraphs later it says (Thunderbeak) "Where's your manners? Dozing off when this nice rabbit is singing you a song?" Also, in the next paragraph, Mariel refers to him also as a rabbit.

Now, if I've been reading correctly, Dandin is NOT a rabbit (or a hare for that matter) and Tarquin would be singing and playing on HIS harolina, the instrument he carries. Therefore, Dandin was not playing on Tarquin's harolina.