Ophthalmosaurus icenicus (Seeley 1874, Mid to Late Jurassic, 6m, 19.5 feet long) had long toothless jaws, a short postorbital region and large eyes. The hind paddles were tiny. Overall the body had a deep dolphin shape, but with vertical tail flukes. Derived from a sister to Guizhouichthyosaurus, Ophthalmosaurus was a sister to Ichthyosaurus. Note the variation within the genus (above).

Seeley HG 1874. On the pectoral arch and forelimb of Ophthalmosaurus, a new ichthyosaurian genus from the Oxford Clay. Quart. J. geol. Soc. London, 30: 696–707.

wiki/Ophthalmosaurus