C. senegalensis in short, more rounded shells (Yankson and Kendall, 2001). Three types of keyhole limpets, family Fissurellidae are encountered on the West African seashore. Diodora menkeana (Dunker) has an aperture length between 6–15 mm; height about half its length and a small apical hole markedly anterior. It has sculpture of intersecting radiating and concentric ridges, color may be cream, pale pink or brown. This species occurs throughout West Africa in shallow and low on rocky shores though rare (Yankson and Kendall, 2001). The genus Fissurella is distinguished from Diodora by its flatter shell, a larger more central apical hole, sculpture of only radiating ridges and height about a third of its length. Species of this genus are found low on the shore attached to rocks from which they scrape minute algae. They rest on open rock and do not seek crevices (Yankson and Kendall, 2001). Two species has been recorded. Fissurella coarctata has a large apical hole and of characteristic shape, color pale pink or brown. It has a length of about 25–35 mm. This species is fairly common in Senegal and Sierra Leone, rare in Ghana and has not been recorded further east (Yankson and Kendall, 2001). Fissurella nubecula has an aperture length of 15–25 mm, medium sized apical hole and color pink or violet often with radiating white bands. This species is common from Ghana eastwards and in Senegal though it seems to be rarer in between. It is commoner in sheltered rather than in exposed areas (Yankson and Kendall, 2001). Siphonaria pectinata (Family: Siphonariidae, described on another page) has an aperture length of 20–30 mm long, slightly less wide, height about half its length or more, sculpture of fine radiating ridges, often worn smooth at apex. This species has a color that is externally dark brown or grey, paler at worn apex, internally shining black at edges, paler at center. It is common at all levels on the West African rocky shores and it rests on exposed shores (Edmunds, 1978). Patella safiana (see Cymbula safiana, family Patellidae) has an oval aperture height about 40–60 mm or more. It is sculptured by radiating ridges, colored grey externally, and blue-grey and white internally, with a horseshoe shaped paler scar, which is interrupted anteriorly to make room for the head. It is found throughout West Africa usually common on open rocks from low to mid shore or sometimes higher