The _Fissurella nimbosa_ is found in various and distant parts of the
world,—in the north of Europe, the western coast of Africa, &c. It is
rather a handsome shell, which seldom exceeds an inch and a half in
length.
[Illustration:
_Umbrella Crepidula Fissurella
Mediterranea. unguiformis. nimbosa._
]
The Fissurella very much resembles our limpet, but differs from it by
having a small, rather oval-formed hole in the summit of the shell,
affording a passage to a small canal through which the water is
discharged, after having passed over the branchiæ.