The difficulties in identifying separate subspecies and species have been pronounced. Hernández-Camacho and Cooper reported some specimens of capuchin from the Barranquilla animal market had supposedly come from the middle valley of the San Jorge River. It is difficult to determine whether these are white-faced capuchins ("Cebus capucinus") or white-fronted capuchins. Intermediate characteristics include a dark crown that is high and removed from the forehead. The white parts on the face are more distinctively bald and the outside parts of the arms and legs are more clear; this suggests they are white-headed capuchin. Some specimens of "C. versicolor" seen in the market at Magangué‚ and probably captured in the lower Cauca River, show similar tendencies to the above, except that there is no increase in the dark pigmentation. Based on these observations and on various "intermediate" specimens from northern Colombia, it is possible that an investigation of the contact zone between the white-headed capuchin and white-fronted capuchin ultimately could show that these forms are conspecific, or that some species of white-fronted capuchin are actually more closely related to white-faced capuchins than they are to other white-fronted capuchins. Another critical zone for this analysis is an area in northeast Ecuador where "C. aecuatoriales" and white-faced capuchins are found, although neither sympatric distributions or intergradation have as yet been determined.