This etymology was later supported by the physician William Baird in the 1820s, who noted that the Dutch word loeris signified "a clown". In 1785, the Dutch physician and naturalist Pieter Boddaert was the first to officially describe a species of slow loris using the name Tardigradus coucang. This species was based on the "tailless maucauco" described by Thomas Pennant in 1781, which is thought to have been based on a Sunda slow loris, and on Vosmaer's description of a Bengal slow loris. Consequently, there has been some disagreement over the identity of Tardigradus coucang; currently the name is given to the Sunda slow loris. The next slow loris species to be described was Lori bengalensis (currently Nycticebus bengalensis), named by Bernard Germain de Lacépède in 1800. In 1812, Étienne Geoffroy Saint-Hilaire named the genus Nycticebus, naming it for its nocturnal behavior. The name derives from the , genitive form of (, "night"), and (, "monkey"). Geoffroy also named Nycticebus javanicus in this work. Later 19th-century authors also called the slow lorises Nycticebus, but most used the species name tardigradus (given by Linnaeus in 1758 in the 10th edition of Systema Naturæ) for slow lorises, until mammalogists Witmer Stone and James A. G. Rehn clarified in 1902 that Linnaeus's name actually referred to a slender loris. Several more species were named around 1900, including Nycticebus menagensis (originally Lemur menagensis) by Richard Lydekker in 1893 and Nycticebus pygmaeus by John James Lewis Bonhote in 1907. However, in 1939 Reginald Innes Pocock consolidated all slow lorises into a single species, N. coucang, and in his influential 1953 book Primates: Comparative Anatomy and Taxonomy, primatologist William Charles Osman Hill also followed this course. In 1971 Colin Groves recognized the pygmy slow loris (N. pygmaeus) as a separate species, and divided N. coucang into four subspecies, while in 2001 Groves opined there were three species (N. coucang, N. pygmaeus, and N. bengalensis), and that N. coucang had three subspecies (Nycticebus coucang coucang, N. c. menagensis, and N. c. javanicus). In 2006, the Bornean slow loris was elevated to the species level (as Nycticebus menagensis) based on molecular analysis of DNA sequences of the D-loop and the cytochrome b gene. In 2008, Groves and Ibnu Maryanto confirmed the promotion of the fifth species, the Javan slow loris, to species status, a move that had been suggested in previous studies from 2000. They based their decision