SHELL OBSERVATION 正確觀察貝殼的方法
There are two methods to observe the shell, firstly, hold shell with care, apex in up position and aperture face to the observer, now, you see the aperture, two posibilities ： 1) Dextral Shell － the aperture is in the right hand side of columella; 2) Sinistral Shell － the aperture is in the left hand side of columella; secondly, followed the same method, but you see the apex. There are two posibilities as well ： 1) Dextral Shell － clockwise spiral from center to edge; 2) Sinistral Shell － counterclockwise spiral from center to edge Umbo up position, the posterior end face to the observer, now the shell in your right hand side is the right shell, the shell in your left hand side is the left shell. You can also watch the inner surface of shell with umbo in up position, right shell － the pallial sinus is in your right hand side; left shell － the pallial sinus is in your left hand sideGastropods observation 
Bivalves observation
