xviii INTRODUCTION. 



J^ortunity of retaliation, by partially destroying the float- 

 ing habitation of the universal despoiler, Man; for the 

 Pholas and Teredo Navalis frequently commit such se- 

 rious injury on ships, by boring into their planks, as often 

 to endanger the safety of the whole fabric, if not speedily 

 prevented in their depredations. 



Directions for collecting Shells, and arranging them 

 systematically. 

 With regard to collecting shells, it is necessary to hint 

 to those collectors, who, by a residence on the sea-coast, 

 may have an opportunity of forming collections for them- 

 selves, that the best way is to select those shells which have 

 the animal alive in them ; for those that are found empty on 

 the beach, are for the most part objectionable, as the 

 shell becomes impaired, and the co-operation of the sun 

 and waters greatly tends to destroy the beauty of the co- 

 loring and marking. 



Besides, a double advantage is to be derived from hav- 

 ing the animals alive, for, by keeping them a few days, 

 (not longer) in sea water, much useful information may be 

 obtained, by an accurate observation of their structure and 

 habits. 



Storms frequently cast up live shells on the beach : such 

 should be collected as soon as convenient, as they fi-e- 

 quently lose their delicate spines and foliations, by being 

 suffered to remain beating about on the shore. 



As land and river shells are seldom so beautifully form- 

 ed, marked, or colored, as those of the sea, they are in 

 consequence rarely so much prized ; however, their pre- 

 sence is absolutely necessary in all collections. 



The collector should keep the following objects in view, 

 whenever he commences the arrangement of his shells: 



