Alvania syngenes is a species of minute sea snail, a marine gastropod mollusk or micromollusk in the family Rissoidae.

[2] (Original description) The small shell is white, long-ovate, with a regularly tapering, blunt-tipped spire.

These are rather finely and regularly reticulated by transverse ribs and revolving cinguli of nearly equal strength, except on the base, which has only the spiral sculpture.

The whole shell, except the nucleus, is covered with well developed, rather thin, revolving cinguli, which are about the same height as the ribs, though rather thinner, but in crossing the ribs they do not form nodules, so that the surface is cancellated with a regular network, of which the meshes are squarish, or elongated in the direction of the revolving lines, but below the periphery of the body whorl the cinguli become stronger and the ribs fainter, while the greater part of the base is occupied with cinguli only, which are here rather closely crowded.

The portion in contact with the body whorl has a free edge, and in the umbilical region the margin is a little reflexed, often leaving a slight furrow beneath it.