BY E. RAYMOND HALL The most popular small game mammal in nearly every part of North America is one or another of the species of rabbits or hares. The rabbit is one of the few species of wild game that still is hunted commercially and sold for food on the open market. The close association and repeated contact of man with these animals has resulted in his contracting such of their diseases as are transmissible to him. Consequently the rabbits and hares have figured in many investigations concerne

Certain characters in which this family differs from the Leporidae (hares and rabbits) are: hind legs scarcely longer than forelegs; ears short, approximately as wide as high; no postorbital process on frontal; rostrum slender; nasals widest anteriorly; maxilla not conspicuously fenestrated; jugal long and projecting far posteriorly to zygomatic arm of squamosal; no pubic symphysis; one less cheek-tooth above, the dental formula being i. 2/1, c. 0/0, p. 3/2, m. 2/3; second upper maxillary tooth

Hind legs longer than forelegs; ears longer than wide; frontal bone carrying supraorbital process consisting always of posterior arm and sometimes of anterior arm; rostrum wide; nasals not wider anteriorly than posteriorly; maxillae conspicuously fenestrated; jugal projecting less than half way from zygomatic root of squamosal to external auditory meatus (except in Romerolagus ); pubic symphysis well marked; dental formula, i. 2/1, c. 0/0, p. 3/2, m. 3/3 (but m. 2/3 in Pentalagus of Liu Kiu Isla

Allen , J. A. 1910. Additional mammals from Nicaragua. Bull. Amer. Mus. Nat. Hist., 28:87-115, April 30. Anderson , R. M. 1947. Catalogue of Canadian Recent mammals. Bull. Nat. Mus. Canada, 102:v + 238, January 24. Anderson , R. M., and Rand , A. L. 1943. A synopsis of the rodents of the southern parts of the Prairie Provinces of Canada. Special contribution-43-1, Canada, Dept. Mines and Resources, Mines and Geol. Branch, pp. 1-25, 13 illustrations (mimeographed MS). On the front of the self cov