17. PTBEONURA. 113 



Lutra hudsonica, F. Cm. Supp. Buffon, i. p. 194, 1831. 



Lutra vulgaris canadensis, Wagner, Schreh. Supp. ii. p, 266. 



Lutra lataxina, F. Cuv. Diet. Soi. Nat. xxvii. p. 243. 



Lataxina mollis, Gray, lAst Mamm. B. M. p. 70. 



Latax lataxina. Gray, Ann. Sr Mag. N. H. i. p. 119, 1837. 



Latax canadensis, Gray, P. Z. S. 1865, p. 133. 



Lutra canadensis, var., et Lataxina mollis, And. Sr Bachm. N. A. 



Quad. iii. p. 976, f. 122, 1853. 

 Lutra califomica, Baird, N. A. Mamm. p. 187 (not Gray). 

 Var. Smaller. 



Lutra destructor, Bamston, Canadian Naturalist, 1863 (%. foot and 

 skuU) ; see Gray, P. Z. S. 1865, p. 133. 



Hah. North America, Canada. 



B. Tail elongate, rather depressed, with a cord-like ridge on each side, 



17. PTERONURA. 

 Head depressed ; ears hairy, small ; muzzle entirely covered with 

 hair. Fur very soft, short, with a fine short soft under-fur. Feet 

 large and strong; toes 5/5, elongate, strong, widely webbed to the 

 ends ; toes on fore feet nearly equal, thumb smaller ; the three 

 outer toes of the hind feet are rather longer than the first toe, and 

 the great toe a little smaller ; claws large, compressed, acute ; soles 

 and palms bald to the heel, striated. Tail conical, tapering, rather 

 depressed, covered with short hair, and furnished with a subcyHn- 

 drical prominent ridge on each side ; end more depressed, two-edged, 

 and fringed at the tip. Teats four, abdominal. Skull elongate, 

 rather high for an Otter; face very short; nose-opening large, 

 nearly erect ; nose with an oblong depression on each side near the 

 orbits ; orbits very incomplete, moderate, with a very large oblong 

 aperture beneath the lower edge, and with an obtuse prominence in 

 the front of the upper edge near the side of the nose ; forehead 

 shelving, flat, straight, sides over the orbits straight and short, 

 triangular behiad the very small conical supraorbital process ; crown 

 with a very narrow central ridge ; brain-case very long, twice as 

 long as the face to the back of the orbits, very narrow and com- 

 pressed in front, broad and swollen behind ; zygomatic arch very 

 strong, broad, leaving a very large wide cavity beneath, infraorbital 

 process slightly marked ; the occipital end nearly erect, nearly twice 

 as broad as high ; the foramen magnum oblong, transverse ; the 

 upper edge of the foramen thick, concave, with two large roundish 

 perforations close together in the upper part for the passage of two 

 blood-vessels to the brain-cavity. Palate rather concave, narrowed 

 behiad, with a square hinder nasal opening. The four central 

 cutting-teeth in each jaw moderate, equal, the outer larger and 

 broader. The premolars conical; the front very small, on the 

 inner side of the hinder edge of the base of the canine ; two others 

 conical, with distinct cingulum. The flesh-tooth large, with the 

 inner lobe nearly as long as the outer edge, oblong, the front side 

 being broadest. The last or tubercular grinder oblong, transverse, 

 nearly twice as broad as long, with four distinct tubercles. The 



