T54 TROCHUS. 



or more in length, one end of which is attached to the 

 throat, and the other, wliich is free, you will see coiled 

 in a beautiful spiral manner, within the cavity of the stomach. 

 By allowing this tiny thread to stretch itself on a plate of 

 glass, which is easily done by putting a drop of water on it 

 lirst, which may then be drained off and dried, you will find 

 that it is in reality an excessively delicate ribbon, of trans- 

 parent cartilaginous substance or membrane, on which are set 

 spinous teeth of glassy texture and brilliancy. They are 

 perfectly regular, and arranged in three rows, of which the 

 middle ones arc three-pointed, while on each of the outer 

 rows a three-pointed tooth alternates with a larger curved one, 

 somewhat boat- like in form. All the teeth project from the 

 surface of the tongue on hooked curves, and all point in the 

 same direction." 



And with this curious piece of mechanism the little Winkle 

 works away and cuts down swathe after swathe of the minute 

 vegetation, just as a mower does the meadow grass; only the 

 moUusk eats as he goes, and so gets paynu-nt for his labour; 

 the man has it in another and to him more usi>ful form. We 

 might tell a ver}' long story about these Tops and Winkles, 

 which are nearly related to each other, but must now pass 

 on to describe the rest of the shells on Plate IV, wliich 

 are the Perspective Solarium, {S. perapectivum,) Fig. 5, the 

 generic name comes from sol — the sun, and viewed perspec- 

 tively, that is, in such a position that the whole top of the 

 shell is at once presented to the view, looking like a flat 

 surfixce, it presents a circular appearance, marked with rings 

 and rays like representations of the sun sometimes do. 



The Variegated Solarium, {S. varicgatum,) Fig. 6, is a small 

 but very pretty shell, somewhat rare. The mollusk is remark- 

 able on account of the singular shape of its operculum, which 

 differs from that of all other species; it is of a cone-shape, and 

 covered from top to bottom with what are called membranous 

 lamelhT, that appear to stand out like little shelves winding 

 up spirally. This singular form of operculum has been long 

 known to naturalists, but it is not until lately that they have 

 discovered to what species of tcstacean it belonged. Let us 

 \\Qxv explain that opereulus is the Latin for a cover or lid. 



