The origin of the Lottiidae is estimated at 121 —261 Ma. A tropical Tethyan origin of Lottiidae was suggested by Nakano & Ozawa (2004). Within the Lottiidae, the species now restricted to the cold waters of the North Pacific are basal. The divergences of Erginus and the clade of Acmaea and Niveotectura are estimated at 103-227 Ma and 98-216 Ma, respectively. During the Middle to Late Jurassic, the bivalves of the East Asian Province were distinct from those of the Tethyan fauna (Hayami, 1987). Similarly, the ammonoid fauna from the boreal Pacific became distinctive in the Middle Jurassic, and was isolated from others by the Late Jurassic (Westermann, 1980). Erginus, Acmaea and Niveotectura likely migrated northeastwards along the coastlines of Laurasia to the Pacific, and adapted to cool water. Erginus is unique among patellogastropods as it is the only genus to brood its larvae. Ersinus mav be a Mesozoic relic in the northern Pacific, since it has a low dispersal capability.

Shell. Conical or cap-shaped, apex positioned between middle and anterior of shell; myostracum horseshoe-shaped, open anteriorly. Animal. Nuchal cavity with single gill; secondary gill (branchial cordon) in mantle groove present in some genera. Radula. Lacking rachidian tooth; with 3 pairs of lateral teeth, and marginal teeth either absent, or present in 1 or 2 pairs.

HABITAT Intertidal and subtidal (to 1000 m); attached to firm substrates such as rock, coral, or hard mud; or epiphytic. Many species associated with areas of high wave action.

Lottiidae is a relatively small family of gastropods with about 35 species in North American waters (Rehder 1981). The Lottiidae, formerly known as the Acmaeidae, is characterized by the simultaneous occurrence of foliated and fibrillar middle-layer shell microstructures and broad and simple radular segments. These segments are associated with the basal tooth plates, which are arranged in a chevron formation and lack uncini (Rehder 1981; Lindberg 1998a). The shells are conic and lack foramens or slits. The shells may be high or low, smooth or sculptured, with the largest acmaeid reaching a diameter of approximately 108 mm. The base of the shell can be almost round to narrow (Rehder 1981; Lindberg 1998a). On the inner surface of the shell is a horseshoe-shaped muscle scar. Lottiids are equipped with a broad muscular foot, necessary for attachment to solid structures in areas with heavy wave action. Limpet shell shapes are determined by the habitat where the limpets live (Lindberg 1998a). Limpets living in high-energy zones tend to produce low shells; in deeper waters, they produce taller and wider shells; and in grass beds, they typically have narrower and shorter shells. Most species live intertidally, where they feed on microscopic plant life growing on rocks (Rehder 1981; Lindberg 1998a). These shells resemble, but should not be confused with, those of members of the Fissurellidae, as limpets do not have an apical hole, fissure, or slit in the shell. On the Texas coast Lotiidae is represented by one species, Patelloida pustulata, which ranges in size from 13 to 25 mm .

Forbes (1850) separated the acmaeids (lottiids)from the patellids, proposing the family Acmaeidae. However, it was not until later studies by Dall (1871), Thiele(1892), and Thiem (1917) that the extent of the anatomical differences between the 2 families was clearly shown. One of these differences was in the radular tooth configuration. The radular dentition of the Patellidae consists of a rachidian tooth followed by 2 to 3 pairs of lateral teeth and 3 pairs of marginal teeth. The lottiid radula lacks a rachidian tooth, always has 3 pairs of lateral teeth, and from 0 to 2 pairs of marginal teeth, depending on the species.

The family Acmaeidae / Lottiidae is distributed throughout the world with the exception of Antarctica and most of the west coast of Africa.