PATELLIDA. 333 
feeding on the sea-weed within reach of their long tongues ; 
during the night-time, however, they make short excursions, 
indicated by the irregular tracks they form in their movements. 
They possess the power of excavating the surface of the rocks ; 
but whether by mechanical attrition, aided by the hard crystal- 
line spicula with which the foot is strengthened, or by the car- 
bonic acid disengaged in respiration, has not been positively 
determined; perhaps both agencies are employed, the latter 
being more effective with limestone rocks, the former when, as 
sometimes occurs, the roosting place is excavated in timber. 
PATELLA, Linn. 
Etym.—Patella, a dish. 
Syn.—Scutellastra, Cymbula, Olana, H. and A. Adams. Erueca, 
Tournefort. Patellites, Walch. Patellaria, Lilhwyd. Cellana, 
H. Adams. 
Distr.—150 sp. World-wide. Fossil, 100 sp.  Silurian—. 
P. cerulea (1xxxiv, 49). 
Shell conical, more or less depressed, oval at the base ; apex 
subcentral or anterior, from which usually radiate ribs, which 
are frequently nodose; mostly crenulated on the inner margin. 
Animal. Foot smooth, branchial lamellez subequal all around. 
The Patellz or limpets are not eaten in the United States, but 
in Europe, especially upon the British Coasts, there is a large 
consumption of them; roasted, boiled or made into soup, they 
are very palatable. They were eaten by primitive man, and the 
shells were formed into ornamental necklaces, occurring in the 
most ancient cromlechs or subterranean burial chambers. They 
are very extensively used as bait also; in Berwick alone, until 
the supply was exhausted, nearly twelve millions of limpets are 
said to have been gathered annually for this purpose—a process 
requiring alertness and skill, for, as Wordsworth says :— 

‘‘And should the strongest arm endeavor 
The limpet from its rock to sever, 
Tis seen its loved support to clasp, 
With such tenacity of grasp, 
We wonder that such strength should dwell 
In such a small and simple shell.’ 
‘“‘ Bouchard-Chantereaux says that he had often seen limpets 
(Patella vulgata) crawling, especially just after the tide had 
gone out. The young limpet moves freely about, and shifts its 
quarters; but after attaining a growth of probably a few days, 
it aflixes itself to a particular spot, which it only quits when 
covered by the sea, on the return of each tide. If it settles on 
a hard and rugged rock, the circumference of the shell is 
moulded to fit the irregular surface of its abode; the base of 
attachment is then bleached. Should the rock be soft, it scoops 
