Lemuria, like Atlantis, is held to be a lost land or continent that sank beneath the ocean. Unlike Atlantis, Lemuria is a hypothesis of modern science, proposed in 1864 by zoologist Phillip Sclater. The fossil record – in this case the Lemurs of Madagascar and India (hence the name) – attests to related animal groups in regions now separated by oceans … which Sclater resolved with the proposal of a former prehistoric land-mass, which then later sank.At the time, such proposals of former land-bridges between regions (and their fossil fauna) now isolated by ocean waters were well-known among scientists. Phillip Sclater did not originate the general idea, but only codified & published the specific instance of Lemuria (other instances exist, world-wide). Systematic study of fossils had by then shown that not only were similar species found on opposite sides of the oceans, but that whole sequences of evolution across large spans of time and involving entire ecosystems, are now (quite-mysteriously at the time) located in widely separated places.
Eventually, the intellectual problem for which Sclater created Lemuria was resolved to the satisfaction of mainstream science and most interested citizens, by today’s well-established theory of Plate Tectonics. At the time, though, it seemed considerably more Parsimonious that vast lands could submerge into the ocean, than that the continents slowly creep in various different directions across the face of the planet. At the time, this was a grave scholastic & scientific conundrum, not unlike that of astronomical Dark Matter, in the late 20th & early 21st centuries.
Lemuria as an idea did not evaporate into the intellectual Aether and go away, when scientific sponsorship of it was withdrawn. It was soon adopted & adapted by the robust Occult Movement with which the science of the day was contemporaneous, offering a conveniently unaccountable setting for assorted Phantasmagoria; the comic book industry later mined the notion in similar fashion. Lemuria has continued to crop up in entertainment and fiction literature. Groups in India find it a useful political approximation of their traditional ethnic claims.