NOTES. 39 



gin, which is sometimes covered with scales. These valves 

 are united bv a cartilage, which enables tlie Chiton to roll toge- 

 ther into a ball like the hedgehog and porcupine, on the ap- 

 proach of danger. As the back alone is defended hy the shell, 

 this ingenious expedient effectually protects the sagacious animal 

 against the attacks of its marine enemies, and perhaps enables it 

 to elude their vigilance, from its resemblance to a pebble when 

 perforated by the waves. The name of the genus Chiton is de- 

 rived from a Greek word, signifying a coat of mail, and aptly 

 expresses the coriated appearance of tlie shell, arising from the 

 position of the valves. — Lumceus. 



Note •= page 7, line 2. 

 Deem not thyself from harm secured, 

 Pholas ! in rock or oak immur'd. 

 The Pholades are found in company, but not in groups, or 

 clusters, as the Lepades, for each individual Pholas is detached 

 from its neighbour, and occupies a separate and distinct habita- 

 tion, for these indefatigable creatures open an entrance into stones 

 and wood, by means of a peculiar secretion with which maternal 

 nature has bountifully provided them. The dwelling of this soli- 

 tary shell-fish is generally oblique to the horizon resembling 

 a truncated cone, terminated with a roundish cavity whicli 

 receives the body of the animal, whilst the furthest end is filled 

 up with a proboscis, or pipe, of a fleshy substance, and conical 

 form, truncated at the end. This pipe the animal usually pro- 

 trudes to the surface of the stone, for the evident purpose of 

 drawing in the sea-water, on which it subsists, and again reject- 

 mg it for a fresh supply. A small green vessel has also been 

 observed in the body of the Pholas, but its use is not yet certain. 

 This pipe when plunged into spirits of wine, assumes a purple 

 color. — Mawe, 



