148 
MAMMALIA, 
colour gray above, and whitish below. Twenty-three feet 
long. 
Genus 5.—Monodon. — Linnaeus. 
Generic Character _Incisors, no canines nor grinders; 
total 2. One or two large, straight, very long and pointed tusks 
inflated in the upper jaw ; shaped like the dolphins ; orifice of 
spiracles united on the top of the head; with a longitudinal 
dorsal projection. 
Monodon monoceros. — The Narwal. 
Plate XXXIV. fig. 4. 
Body bovid ; head one fourth the length of the animal; left 
tusk only developed, spirally twisted, half as long as the body; 
marbled black and gray. Twenty-two feet long. Inhabits the 
Northern Ocean. 
Tribe II.— Large-Headed Cetacea. 
Genus 6.—Physeter. — Linnaeus. 
Generic Character .—Lower jaw elongated, narrow, corres¬ 
ponding to a furrow in the upper, with from 18 to 25 thick 
conical teeth on each side; upper jaw broad, elevated, with 
bony laminae, or having short and undeveloped teeth; orifice 
of spiracles united at the upper end of the snout; some spe¬ 
cies with a dorsal fin, others have simple eminences ; upper 
part of the cranium having cartilaginous cavities, filled with oily 
matter, which chrystalises when cool, forming spermaceti. 
Sub-Genus 1.— Catodon. — Lacepede .—Orifice of spiracles 
placed at the extremity of the upper part of the muzzle; with¬ 
out dorsal fin. 
Physeter macrocephalus .— The Great-Headed Cachalot. 
Plate XXXIV. fig. 3. 
Head very large ; from 20 to 23 curved and pointed teeth in 
