A Beluga ('Delphinapterus catodon) and a Narwhal. (Monodon monoceros), L.

Plate 6. The White Whale, or Beluga. Delphinapterus catodon, (L.) Gill. The Narwhal. Monodon monoceros, L.

http://www.photolib.noaa.gov/historic/nmfs/figb0262.htm

Source: https://commons.wikimedia.org/wiki/File:Narwhal_and_Beluga.jpg

The beluga whale or white whale (Delphinapterus leucas) is an Arctic and sub-Arctic cetacean of the family Monodontidae. This white whale is also known as the beluga, melonhead, or sea canary.

The narwhal, narwhale, unicorn whale (Monodon monoceros), is a medium-sized toothed whale that possesses a large "tusk" from a protruding canine tooth. It lives year-round in the Arctic waters around Greenland, Canada, and Russia.