1 08 SEALS. -SHELLS.— SHIPS. 



SEALS. 



Sphrag"is'tics (Gr. aphragk, a seal). — The science of seals, 

 their history, age, distinctions; a branch of diplomatics. 



SHELLS. 



Conchorogy (Gr. kogche, a shell, and logon., a discourse). — The 



doctrine or science of shells and of the animals inhabiting 



them. 

 The upper part of the shell is the qrire, and the point of this 



the apex. The whorls twist round a central axis, or col- 



vmella. The mouth of the shell is termed the aperture. 



The margin, with its outer and inner, or columellar lips, is 



styled the peristome. 

 Conchyliom'etry (Lat. conchih'ion, a shell-fish, and Gr. metron, 



measure). — The science of measuring shells or their curves. 

 Bys'sus. — A tuft or thread of fibres by which the mytilus, 



pinna, and other shells are attached to contiguous bodies. 

 Di'aphragm. — A straight calcareous plate which divides the 



cavity of certain shells into two parts only. 

 Dor'sum. — The upper surflice of the body of a shell, when it is 



so held that the aperture is downward. 

 Fau'ces. — That portion of the first chamber of a shell which 



can be seen by looking in at the aperture. 

 La'brum. — The outer lip of a shell, or that one farthest from 



the axis. 

 Oper'culum. — The lid closing the aperture of various species 



of snails' shells, as the common whelk. 

 Si'nus.— A groove or cavity. 

 Umbiricus. — A conical depression at the base of a univalve 



shell. 

 Var'icus. — Ridges on the outside of a shell which indicate the 



diiferent stasies of ijrowth. 



SHIPS. 



Naviga'tion (Lat. navis, a ship). — The science or art of con- 

 ducting ships or vessels from one place to another. 



Bearing. — To take bearings is to ascertain the points of the 

 compass on which objects lie. 



