- Venice, 1496, showing the ventricles of the brain
- Various species of Trypanosoma from the blood of mammals, birds, and reptiles
- Upper Side of Epeira Vulgaris
- Upland Plover
- Unusual Long Haired Cat
- Unio Batava
- Two-year old Southdown sheep
- Two-humped Camel
- Two Species of Caprellidæ
- Two puppies and a cat
- Two horses looking at their food
- Two horses
- Two girls feeding a cow
- Two dogs and a horse
- Two deer
- Two common centipedes
- Two children riding ponies on the beach
- Two cats running
- Two cats
- Twisted Lime worm ( Serpula contortuplicata )
- Tutored Bear.—XIV. Century
- Tutored Bear.—XIV. Century
- Turtle
- Turkey Vulture
- Tufted Titmouse
- Trypanosoma Ziemanni, from the gut of the gnat
- Trypanosoma Ziemanni, from the blood of the little owl
- Trout
- Trotting across a field
- Tree-porcupine
- Tree Swallow
- Trapping a polar bear
- Tortoiseshell-and-white Cat, finely marked
- Tortoise Shell Manx
- Title-page of Mellerstadt’s edition of the Anatomy of Mondino, Leipzig, 1493. The scene is laid in the open air
- Tired of play
- Tiger snake
- Three Spined Stickleback
- Thirteen-Spotted Lady Beetle
- Thelemark cows of Norway
- The ‘Wonderful Cynocephalus’
- THE ZOEA OF THE COMMON CRAB
- The Zoëa Larva of a Species of Sergestes
- The young of the common Eel and its metamorphosis
- The yellow fever mosquito (Aëdes calopus)
- The Woolly Kangaroo
- The White Yak of the Asiatic Mountains
- The unicellular parasite Benedenia, from the gut of the common Poulp or Octopus
- The two wise cart-horses
- The Two White Birds
- The Three-banded Armadillo. An Animal in a Coat of Mail
- The Tasmanian 'Mountain Shrimp'
- The Surinam Toad
- The Surface of the Left Cerebral Hemisphere, Cerebellum,and Medulla Oblongata.
- The Striped Zebra of Africa
- The Starling. One of the Talking Birds
- The Spine
- The Skull and Brain-Case of Pithecanthropus
- The Skull
- The short strap in use