What is "eques lanceolatus"

Horseman \Horse"man\, n.; pl. Horsemen.

1. A rider on horseback; one skilled in the management of horses; a mounted man.

2. (Mil.) A mounted soldier; a cavalryman.

3. (Zo["o]l.)

   1. A land crab of the genus Ocypoda, living on the coast of Brazil and the West Indies, noted for running very swiftly.

   2. A West Indian fish of the genus Eques, as the light-horseman ( Eques lanceolatus).