122 UNIVALVES. 



A rock, whence fruits celestial grow 



And whence refreshing waters flow 



No rock is like this rock of ours ! 



Oh then if you have learnt your pow'rs 



By a just rule to estimate ; 



If justly you can calculate, 



How great your need, your strength how frail, 



How prone your best resolves to fail, 



When humble caution bids you fear 



A moment of temptation near, 



Let wakeful memory recur 



To this your simple monitor, 



And wisely shun the trial's shock 



By clinging closely to your rock. 



PATELLA GTOBCO. 

 CANCELLATED LIMPET. 



Specific character. Shell ovate, thick, opaque, 

 strongly reticulated,* some of the longitudinal 

 ridges much coarser than the rest, and frequently 

 tuberculated by the crossing of the transverse 

 striae ; apex lateral, not much elevated, truncated 

 and furnished with an oblong perforation ; colour 

 pale, dull brown, or yellowish white ; inside 

 smooth, white, sometimes rayed with dull red or 

 brown ; margin crenated, sometimes indented ; 

 length about three-quarters of an inch, breadth 

 scarcely half an inch, height a quarter. It is 

 rarely found on the British coasts of a superior 

 size ; some of the foreign specimens are an inch 

 long. 



* Reticulated, crossed like net work, from the Latin reticul 

 MW, a small net. 



