438 
THE OCEAN WORLD. 
exposed to the beating waves, 
in all seas. 
Chiton magnificus (Fig. 299) is found 
Fig. 299. Chiton mugtiilieus 
(Deshayes). 
The Fatellidse, or Limpets, constitute a very 
numerous family, distinguished at once by the 
form and structure of the animal, and by that 
of the shell. It was indebted to the ancients f° r 
its vulgar name of Limpet, which Linnaeus changed 
to Patella, or little plate, although the majority 
of the species have little resemblance to a plate, 
large or small. 
The shell of the Patellidse is univalve, oval, or 
circular, non-spiral, but terminating in an ellipt 1 ® 
cone, concave and simple beneath, non-pierce c 
at the summit, entire and inclined anteriorly. ^ 
is smooth, or ornamented on the sides with ridges radiating from the 
summit, and often covered with scales ; the edges are frequently dentate- 
The colours are vivid and much varied. The interior is very smooth, 
and remarkable for the brilliancy and vigour of its tints. 
The head of the animal is furnished with two pointed tentacle 
or horns, having an eye at the external base of each. The body lS 
oval and nearly circular, conical, or depressed. The foot is in tb® 
form of a thick fleshy disk. Certain lamellar branchiae are arrang e 
in series all round the body. 
The Limpets dwell upon the sea shore, in the parts alternately 
covered and uncovered by the waves. They are almost always 
attached to rocks, or other submerged bodies, to which they adhei® 
with great tenacity. If the Limpet is touched before any attempt & 
made to dislodge it, no human force, it is said, can remove it witho 11 
breaking the shell. We are assured that a Limpet can sustain without 
yielding a weight of many pounds weight. It holds on by the g re ‘ l 
quantity of vertical iibres of the loot, wdiich in raising the median p al 
forms in the centre a sort of sucker. It is the celebrated experim®» 
of the Magdeburg cups which these little molluscs realise by the 11 
vital action. 
These animals bury themselves in the chalky rocks to the dep ■ 
of two or three lines ; when they are dispersed, they are observe 
constantly to return to the same place. Their movements are, 
besides 
extremely slow; the advance of the Limpets being only perceive 
