In 1820, the eccentric naturalist Constantine Samuel Rafinesque, then a professor of botany and natural history at the University of Transylvania in Lexington, Kentucky, erected a new genus for a group of slugs native to the northeastern U.S.1
["N. G." = New Genus.]
He also described four new species of Philomycus, including the one below.
As Pilsbry2 noted, the slug Binney3 illustrated as Tebennophorus caroliniensis in his 1857 compilation of the terrestrial mollusks of the U.S. was actually Rafinesque's Philomycus flexuolaris.
Although brief, Rafinesque's description of the color of Philomycus flexuolaris and the patterns on its back are fairly accurate. I saw several of these slugs last weekend during the BioBlitz at New Germany State Park in Garrett Co., Maryland. My specimen in the photograph below was about 65 mm long, within Rafinesque's range. Rafinesque's statement that Philomycus "differs from Limax by no visible mantle" indicates that he didn't realize that in these slugs the mantle covers the entire back.
1. Rafinesque, C.S. 1820. Annals of Nature, First annual number, p. 10. Philadelphia.
2. Pilsbry, H.A. 1948. Land Mollusca of North America (north of Mexico ). Volume 2, Part 2, p. 758. Academy of Natural Sciences, Philadelphia.
3. Binney, A. 1857. The terrestrial air-breathing mollusks of the United States. Vol. III. Little Brown & Co.