Caudad of the canines there is in each jaw a considerable interval free from teeth: this is called the =diastema=. Caudad of the diastema are the =premolar= teeth, three pairs (_c_, _d_, _e_) in the upper jaw and two pairs (_c_, _d_) in the lower jaw. These teeth are compressed sideways, and those of the lower jaw fit inside of those of the upper jaw. In the =upper= jaw (Fig. 93) the first premolar (_c_) is small and usually has but a single cusp and a single fang, though occasionally there is a small supplementary cusp and fang. The second premolar is larger (_d_); it has a large central cusp, with a single smaller cranial cusp and two small caudal cusps, making four in all. This tooth has two fangs. The third premolar (_e_) is the largest tooth in the jaws; it has three large cusps in longitudinal series and a small cusp lying on the medial side of the first one in the row. Its root has three fangs. The =molar= tooth (_f_) of the upper jaw is small and lies caudomediad of the last premolar. It has two small cusps and two fangs. [Illustration: FIG. 94.--MANDIBLE, WITH ROOTS OF THE TEETH LAID BARE. _a_, incisors; _b_, canine; _c_, first premolar; _d_, second premolar; _f_, molar.] In the =lower= jaw (Fig. 94) the two premolars (_c_ and _d_) are similar, the caudal one being a little larger. Each has four cusps; a single large one, a small one craniad of this, and two small ones caudad of it. Each has two fangs. The single molar (_f_) is the largest tooth of the lower jaw; it has two large cusps and two fangs. =The Deciduous Teeth.=--At birth the cat has no teeth. There appears later a set of twenty-six teeth: twelve incisors, four canines, and ten molars (six in the upper jaw and four in the lower). These teeth are later replaced by the permanent ones above described. The deciduous teeth of the cat are fully described by Jayne (“Mammalian Anatomy,” vol. 1. p. 319), where also an account is given of the order of appearance of the teeth.