( Fig. 5d)
Notomastus tenuis Moore, 1909: 277, pl. 9, fig. 55.— Berkeley & Berkeley 1952: 103.— Fauchald 1972: 248.— Blake 2000: 85, fig. 4.15.— Dean 2001: 81; 2004: 147.— Hernández-Alcántara & Solís-Weiss 1998: 712; 1999: 27; 2003: 4.—García- Garza & de León-González 2011: 44.— Magalhães & Bailey-Brock 2012: 39, fig. 28c–e, 29a–d, 30a–f.— García-Garza et al. 2012: 7, figs 1e–h, 2e–f.
Notomastus angulatus Chamberlin, 1919: 16 –17.— Berkeley 1929: 312.
Eisigella tenuis Berkeley & Berkeley, 1942: 198.
Notomastus ( Clistomastus) angulatus Hartman-Schröder, 1965: 150, fig. 78.
Notomastus ( Clistomastus) tenuis .— Hartman 1947: 420, pl. 47, figs 1–5; 1969: 397, figs 1–5.— Reish 1968: 89.— Kudenov 1975: 220.— Calderón-Aguilera & Jorajuria-Corbo 1986: 55, fig. 8a–c.
? Notomastus tenuis.— Ewing 1984: 14 –26.
Notomastus americanus Day, 1973: 100, figs 13 l–n.— Hernández-Alcántara & Solís-Weiss 1993: 1034; 1998: 710–711; 1999: 27; 2003: 4.
Type material: * Holotype (CAS-019718).
Type locality: Eastern Pacific, USA, California, San Diego, intertidal.
Records: USA, California ( Hartman 1947; Berkeley & Berkeley 1952; Blake 2000); Costa Rica ( Dean 2001, 2004); Hawaiian Islands ( Magalhães & Bailey-Brock 2012).