The dark band on the neck is complete in four of the paratypes and incomplete (as in holotype) in one. Pale marks on the prefrontals are lacking in three of the paratypes and the pale mark between the parietals is lacking in two specimens (fused with white band on neck of one specimen). Pale postnarial crescents are evident in three paratypes. As stated above, the rings on the holotype are mostly complete. Exceptions occur between the 13th and 15th white rings where two black rings are fused on the left side, rendering one black and one white ring (the 14th) incomplete. Also, where the ninth and tenth white rings fuse on the left side, they enclose a black ring and render it incomplete. The markings of the three smaller paratypes are substantially the same as those of the holotype--complete rings with a small number of variations in each specimen. In the two largest paratypes nearly all the white rings are incomplete ventrally, appearing to have been encroached upon by the darker ground color. In the larger speicmens there is a tendency also for the white rings to be one scale wide (rather than alternately one and two scales wide) and to lack a zigzag appearance; this appears to be due to the darkening of entire scales and to the darkening of the edges of other scales. _Relationships._--_Geophis aquilonaris_ is distinct from all other Mexican representatives of the genus in having, on the body and tail, numerous, alternating pale and dark bands. Both sets of bands are in the form of complete rings or the dark bands are joined ventrally rendering the belly dark.