Fig. 4.
The Common Rock-Limpet (Patella vulgata). British.
1. Animal: a, foot; b, fringed mantle; c, tentacles; d, mouth; e, eyes; f, gills.
2. Side view of shell, showing the impression or scar of the attachment-muscle, g.
3. Upper surface of the shell.
Case 8.
The “Keyhole Limpets” and “Slit Limpets” (Fissurellidæ) resemble in external shape ordinary Limpets, but are perforated at or near the apex, or more or less slit at the front margin. The hole or slit gives passage to a tubular fold of the mantle, through which the water apparently flows to the gills. The largest species are from California and South America, and others are found, but not abundantly, on most shores. The animal of the large Lucupina crenulata from California is eight or ten inches in length, and almost conceals the shell, and the shell of the South-African Pupillæa aperta is also all but hidden beneath the mantle of the animal.
Fig. 5.[[3]]
Pleurotomaria adansoniana. Case 9.
⅓ natural size.
Case 9.
The Pleurotomariæ are extremely rare in recent times, only five species being known, whereas over a thousand fossil forms have been described. The specimens of P. adansoniana and P. beyrichi exhibited in case 9, are among the finest acquisitions to the shell collection of recent years.
Cases 9–11.
The “Ear-shells” or “Ormers” (Haliotidæ) are found adhering to rocks in most parts of the world, with the exception of South America. They are lined with pearl, and many exhibit splendid colours and sculpture externally. Like the Limpets they hold on to the rocks with such tenacity that it is absolutely impossible to remove some of the larger species by force without injuring the shell. Boiling water or mustard and water poured over them will, however, soon compel them to relinquish their hold. The shell of Haliotis is pierced by a series of holes parallel with the left margin. Through such of them as are open the animal protrudes a slender filament or feeler, and the water also finds its way through them to the gills beneath.