Which of these is the smallest of the sea turtles?

Kemp's ridley sea turtle, also called the Atlantic ridley sea turtle, is the rarest species of sea turtle and is critically endangered. It is one of two living species in the genus Lepidochelys.

This species of turtle is called Kemp's ridley because Richard Moore Kemp (1825-1908) of Key West was the first to send a specimen to Samuel Garman at Harvard. However, the etymology of the name "ridley" itself is unknown. Prior to the term being popularly used (for both species in the genus), L. kempii at least was known as the "bastard turtle".

Kemp's ridley is a small sea turtle species, reaching maturity at 58–70 cm (23–28 in) carapace length and weighing only 36–45 kg (79–99 lb). Typical of sea turtles, it has a dorsoventrally depressed body with specially adapted flipper-like front limbs and a beak. Kemp's ridley turtle is the smallest of the sea turtles, with adults reaching a maximum of 75 cm (30 in) in carapace length and weighing a maximum of 50 kg (110 lb). The adult has an oval carapace that is almost as wide as it is long and is usually olive-gray in color.