APPENDIX. %$5 



** Digitigrada. Treading on the extremities of their digits. 



a. Only one tuberculous behind the upper carnivorous tooth : 



body much elongated, vermiform: feet short. 

 Genus 10. Mustela. Toes cleft: tail moderate and bushy. 

 Genus 11. Mephitis. Toes cleft: tail long- and bushy or wanting. 

 Genus 12. Lutra. Toes palmated. 



b. Two tuberculous behind the upper carnivorous tooth. 

 Genus 13. Canis. Feet 5 — 4 toed; nails not retractile: tongue smooth. 



c. No small tooth behind the inferior large molar. 



Genus 14. Felis. Feet 5 — 4 toed : nails retractile : tongue prickly. 



FAMILY MARSUPIALIA. 



Genus 15. Didelphis. 



ORDER PINNIPEDIA. 



FAMILY PINNIPEDIA. 



Genus 16. Phoca. Both jaws furnished with incisive and canine teeth. 

 Genus 17. Trichecus. No incisors nor canine below; superior canine 

 greatly prolonged below the lower jaw. 



ORDER GLIRES. 



FAMILY MURINI. 



Genus 18. Castor. Feet five toed, anterior cleft, posterior palmated; 



tail wide, depressed, thick, oval, naked and scaly. 

 Genus 19. Fiber. Feet five toed, anterior simple, posterior furnished 



with stiff bristles replacing the membrane; tail compressed, 



linear, scaly, with scattered bristles. 

 Genus 20. Arvicola. Feet simple; tail cylindrical, hairy, grinders 



without radicles. 

 Genus 21. Neotoma. Feet simple; tail cylindrical, hairy: grinders with 



profound radicles, and with small marked triangles. 

 Genus 22. Sigmodan. Feet simple; cylindrical, hairy: molars in each 



jaw, six, subequal, with radicles, and with deep, alternate 



folds towards the summit. 

 Genus 23. Mus. Feet simple; tail cylindrical, subnaked, scaly, with 



scattered hairs. 

 Genus 24. Gerbillus. Hind feet very long, five toed, each furnished 



with a distinct metatarsal bone; tail elongated, more or less 



bushy, but without tuft at tip. 



