presented, based on different species, some of which went through a metamorphosis, and some of which did not. In 1828 John Vaughan Thompson published a paper "On the Metamorphoses of the Crustacea, and on Zoea, exposing their singular structure and demonstrating they are not, as has been supposed, a peculiar Genus but the Larva of Crustacea!!" However his work was not believed due to crayfish not undergoing metamorphosis. This controversy persisted until the 1840s, and the first descriptions of a complete series of larval forms were not published until the 1870s (Sidney Irving Smith on the American lobster in 1873; Georg Ossian Sars on the European lobster in 1875, and Walter Faxon on the shrimp Palaemonetes vulgaris in 1879). Larval stages Nauplius The genus name Nauplius was published posthumously by Otto Friedrich Müller in 1785 for animals now known to be the larvae of copepods. The nauplius stage (plural: nauplii) is characterised by consisting of only three head segments, which are covered by a single carapace. The posterior body, when present, is unsegmented. Each head segment has a pair of appendages; the antennules, antennae, and mandibles. This larval stage has various lifestyles; some are benthic while others are swimmers, some are feeding while others are non-feeders (lecithotrophic). The nauplius is also the stage at which a simple, unpaired eye is present. The eye is known for that reason as the "naupliar eye", and is often absent in later developmental stages, although it is retained into the adult form in some groups, such as the Notostraca. Some crustacean groups lack this larval type, isopods being one example. Zoea The genus Zoea was initially described by Louis Augustin Guillaume Bosc in 1802 for an animal now known to be the larva of a crab. The zoea stage (plural: zoeas or zoeae), only found in members of Malacostraca, is characterised by the use of the thoracic appendages for swimming and a large dorsal spine. Post-larva The post-larva or Megalopae, also found exclusively in the Malacostraca, is characterised by the use of abdominal appendages (pleopods) for propulsion. The post-larva is usually similar to the adult form, and many names have been erected for this stage in different groups. William Elford Leach erected the genus Megalopa in 1813 for a post-larval crab; a copepod post-larva is called a copepodite; a barnacle post-larva is called a cypris; a shrimp post-larva is called a parva; a hermit