What is "hypolagus"

Hypolagus is an extinct genus of Lagomorpha, first recorded in the Hemingfordian (early to middle Miocene) of North America. It enters Asia during the early Turolian and spreads to Europe not much later, where it survives until the Middle Pleistocene. Though unknown in the Iberian Peninsula, fossils of this genus have been found in the Balearic Islands, suggesting an eastern migration during the dry period in the Mediterranean region known as the Messinian Salinity Crisis.