and Picas in the British Museum. 221 



strong. Skull high, more or less compressed ; the uose arched ; 

 maxillse netted in front of the orbits. Cutting-teeth (upper) 

 with a subccntral groove ; molars | • ^, each formed of two plates 

 united by enamel, except the upper hinder one, \yhich is small 

 and formed of only one plate. The upper hinder grinder is like 

 the third plate in the former family ; but it is distinct, forming 

 a separate tooth. 



Section I. STcull high, rather compi'essed. Nose compressed ; cheeks 

 nearly fiat, separated from the orbits by a strong ridge, and edged 

 above by the prominent upper hiyider elongated process of the in- 

 ter maxillaries. Orbits large, roundish. Cutting-teeth moderate. 



A. Hares. The hinder nasal aperture of skull broad, deep, 

 rounded above, and with nearly erect sides. Young born xoith 

 the eyes open and the body covered with hair. Living in "for^ns" 

 on the surface of the earth. 



I. Postorbital process more or less soldered with the skull. 



1. Hydrolagus. Lepus § F, Baird, N. A. M. 575. Feet very 

 short, weak, covered with scattered hairs, exposing the toes ; claws 

 acute. Skull and incisors comparatively large and massive; muzzle 

 about as wide as high. Postorbital process completely fused 

 into the skull for its entire length, leaving neither foraminal 

 notch nor suture. " Water-Hare." 



* Tail elongate, white beneath. 



1. Hydrolagus aquaticus. {Lepus aquaticus, Bachm. J. A. N. S. 

 Philad. vii. 319, t. 22. f. 2; Baird, N. A. M. 612. t. 59. f. 1 

 (skull). L. Douglasii, var. 1, Gray, Mag. N. H. 1837, p. 586.) 



** Tail very short, dusky beneath. 



2. Hydrolagus palustris. {Lepus palustris, Bachm. /. c. t. 25, 

 26; Baird, N. A. M. 615, t. 59. f. 2 (skull). L. Douglasii, 

 var. 2, Gray, Mag. N. H. 1837, p. 586.) 



2. Sylvilagus. Lepus § D, Baird, N. A. M. 575. Skull 

 about twice as long as wide, very convex and much arched be- 

 hind ; muzzle rather wider than high. Postorbital process mo- 

 derate, united behind and laterally by anchylosis with the skull, 

 with a distinct suture bounding a small narrow foramen in 

 front. Cutting-teeth narrow. Mind feet nearly as long as the 

 head. Burrows for protection (Clark). 



* Soles very densely furred. 



1. Sylvilag us nanus. {Lepus nanus, Schreh.t. 234} b ; Dekay. 

 L. americnnus, Desm. Lepus sylvaticus, Bachm., Waterh. Gl. 

 116; And. N. A. Q. t. 22; Baird, N. A. M. 600, t. 58. f. 1 

 (skull).) Grey Rabbit. B.M. 



