The bacula of North American sciurids are divisible into six distinct types represented by those of the genera Spermophilus, Marmota, Sciurus, Tamiasciurus, Eutamias, and Glaucomys.

Sir John Richardson told me that the species was Spermophilus Parryi.

The large tribe, of the marmots, which includes the three large genuses of Arctomys, Cynomys, and Spermophilus, is still more sociable and still more intelligent.