§ I. Incisor, canine, and molar teeth all present, forming a continuous series.

Feet armed with strong claws: mammae abdominal: penis sheathed.

* Six incisors in each jaw: grinders of three sorts.

† Walk on the soles of the feet.

1. Ursus

Lower incisors set in the same line: grinders varying in number, the three last large and tubercular: no glandular pouch under the tail.

2. Meles

Second incisor on each side in the lower jaw placed behind the others: grinders five above and six below on each side; the first very small, the last tubercular: body low on the legs: a glandular pouch or scent-bag under the tail.

†† Walk on the extremities of the toes.

3. Mustela

Grinders varying in number : body very much elongated: feet short; the toes separate: ears short and rounded.

(1. Mustela). Grinders five above and six below on each side: tongue smooth.

(2. Putorius). Grinders four above and five below on each side; tongue rough.

4. Lutra

Grinders five above and five or six below: body long: feet short, with five palmated toes: head depressed : ears very short: tongue slightly rough: tail flattened horizontally.

5. Canis

Grinders six above and seven below on each side; the two last in each jaw tubercular: ears moderately large: tongue smooth : claws not retractile.

(1. Canis). Pupil circular.

(2. Vulpes). Pupil linear: tail bushy.

6. Felis

Grinders four above and three below on each side ; no tubercular grinder in the lower jaw : tongue armed with prickly papillae pointing backwards: claws retractile.

** Teeth various: feet short and fin-shaped, adapted to swimming; those behind horizontal.

7. Phoca

Incisors and tusks in both jaws: grinders uniform ; each of three lobes ; the central lobe triangular, large and cutting, the anterior and posterior lobes small.

8. Trichechus

No incisors or tusks in the lower jaw: tusks in the upper jaw greatly produced, directed downwards: grinders cylindrical, short, and obliquely truncated.

*** Incisors varying in number: summits of the grinders with conical points: soles of the hinder feet applied to the ground.

9 Talpa

Incisors six above and eight below, nearly equal: tusks large: grinders seven above and six below on each side : body very thick : fore feet short and broad, formed for digging: tail short: no external ears: eyes very minute.

10. Sorex

Two middle incisors produced beyond the others; those above bent and notched at the base: lateral incisors or false tusks very small: grinders four above and three below on each side: body covered with hair: snout attenuated: tail long.

11. Erinaceus

Two middle incisors produced beyond the others, longer than the tusks; those above cylindrical, with a space between: grinders five above and four below on each side: body covered with spines: tail very short.