60 Beautiful Shells. 
beings, sloth covers and hides the good qualities 
and virtues with an overgrowth ai all times difficult 
to remove, and oftentimes destructive of all that is 
fair and good in the character.—Children, be not 
slothful! The Obelisk Trochus (T. obeliscus), is a 
rare white and green shell, sometimes seen in collec- 
tions; it is of a conico-pyramidal form, not remark- 
able for beauty, and is a native of the Indian seas. 
Mr. Gosse speaks of the Tops and Winkles as 
among the most useful inhabitants of the Aquarium ; 
they mow down with their rasping tongues the 
thick growth of Conferve, which would otherwise 
spread like a green curtain over the glass walls of 
the tank, and obstruct the view of its inhabitants. 
Here is this author’s description of the beautiful 
piece of mechanism by which this work is effected :— 
«The appearance and position of the organ would 
surprise any one who searched for it for the first time ; 
and as it is easily found, and as Periwinkles are no 
rarities, les me commend it to your examination. 
‘The easiest mode of extracting it, supposing you are 
looking for ié alone, is to slit the thick muzzle 
between the two tentacles, when the point of a 
needle will catch and draw out what looks like a 
slender white thread, two inches or more in length, 
one end of which is attached to the throat, and the 
