Abstract: Means to feed material to be sieved into the receiving end of an open-ended, substantially horizontal, rotary sieving sleeve, comprise a trunk disposed coaxially with the sleeve and having a material-receiving end outside the sleeve and the other end portion projecting into the sleeve by an amount equal to from one half to one quarter the length of the sleeve. The portion of the trunk within the sleeve has a material departure aperture formed in the top of that portion. This aperture is in the form of a horizontal weir which extends axially of said portion for a distance at least equal to half the axial length of said portion measured from the innermost end thereof.