A. new sf) ecies of a diogenid hermit crab, Calcinus urabaensis, is described from the Gulf of Uraba, on the Caribbean coast of Colombia. The new species is the third in the genus described from the western Atlantic, and can be distinguished from the other two known species of the genus Calcinus in the region, C. tibicen (Herbst) and C. verrilli (Rathbun), by differences in coloration and armature of the dactyl of the left cheliped, third pereopod, and telson. A comparison of the three species is included./? e5Mm^«.—Se describe una nueva