THE 



BRITISH ENCYCLOPEDIA. 



CONCHOLOGY. 



ft ONCHOLOG Y. The study of shells, 

 \J or testaceous Animals, is a branch of 

 natural history, though not greatly useful 

 in human economy, yet, perhaps, by the 

 beauties of the subjects it treats of, is 

 adapted to recreate the senses, and in- 

 sensibly lead to the contemplation of the 

 glory of the Divinity in their creation. 



Shells appear to form a part of the cre- 

 ation not immediately subservient to the 

 purposes of human life This being ad- 

 mitted, still they are a link in the great 

 chain of nature ; they constitute a depart- 

 ment of rational enquiry worthy the re- 

 searches of the man of science ; and when 

 we consider the amazing diversity of sin- 

 gular and beautiful objects they embrace 

 are such, we are persuaded, as cannot 

 fail to arrest, in a particular degree, the 

 regard of every common observer. 



The term conchology comprehends the 

 study of all animals which have a testace- 

 ous covering, whether inhabitants of the 

 marine element, fresh water, or the land. 

 Testaceology is a term synonymous with 

 conchology, but is of later origin and ap- 

 plication. 



A precise distinction should be drawn 

 between testaceous and crustaccous ani- 

 mals ; they are essentially different, 

 though both are protected by a hard ex- 

 terior sheU or crust, in which they are 



partially or entirely enveloped, and have 

 been indiscriminately confounded toge- 

 ther, for that reason, under the vague 

 denomination of shell fish. Some of the 

 old writers distinguish the testacea as a 

 kind of stone-like calcareous covering or 

 habitation, in which the animal, other- 

 wise naked, resides, and from which it 

 can protrude its molluscous arms, or 

 other naked parts of its body, at plea- 

 sure. The crustaceous animals of those 

 authors, on the contrary, are not naked, 

 but have every particular limb or part 

 separately covered with the crust, which 

 is thus divided into many joints, inso- 

 much that the whole animal assumes a 

 loricated appearance, as if inclosed in a 

 coat of mail. Among the crustace otis or- 

 der, the cancri, or crabs and lobsters, 

 were included. A better definition may 

 be obtained, by attending to the chemi- 

 cal properties of the two substances tes- 

 taceous and crustaceous. Poli, in his 

 work on the shells of the two Sicilies, de- 

 monstrates that testaceous bodies consist 

 of calcareous earth united to a small por- 

 tion of animal matter or gluten; and Mr. 

 Hatchett, whose experiments on the che- 

 mical characters of those bodies are in- 

 serted in the Transactions of the Royal 

 Society, draws a striking distinction from 

 analysis between the testaceous and crus- 



