iv PREFACE 



whose members are prone to almost indefinite individual variation, it 

 is exceedingly doubtful if material will ever be gathered together 

 sufficient to enable the question, of how many separate forms actually 

 do exist, to be satisfactorily and definitely determined. 



A number of the types of the earlier describers, as well as some 

 of later date have disappeared, and on account of this misfortune the 

 species they represented cannot be established, and this is especially 

 unfortunate when the name given has, for many years, been adopted 

 and applied to the evidently wrong animal. To correct such errors 

 will probably be a slow process, as it is difficult to overcome a bad 

 habit once formed. Again numerous examples that served for types, 

 by the passing of the many years since they received their names, have 

 so deteriorated — from the accumulation of dust, the loss of their fur, 

 and fading of their colors from unwise exposure to light — as to be no 

 longer recognizable or of any value as the special representative of 

 some particular species, and such cases are particularly to be regretted 

 when the original description was so brief as to convey but a faint 

 idea of the appearance of the animal. 



The earlier writers seem to have depended mainly for the charac- 

 ters of their species on the colors of the pelage and its distribution, 

 and rarely considered the more important characters of the crania. 

 Their limited material gave them no idea of the great variation, mainly 

 individual, that existed in the coloring of the pelage among members 

 of niunerous genera, and so were misled into believing their examples 

 represented more than one species, when it was only the individual 

 eccentricities of a very variable form that they were unknowingly 

 considering. 



Notwithstanding the vast accumulation of examples of the Pri- 

 mates from all parts of the world in the last twenty years, a number 

 of important facts cannot yet be settled, nor will they be until much 

 additional material is received. 



In the recognition of apparently distinct forms, subspecies in only 

 comparatively few cases have been accepted, because intermediates 

 between what are recorded as species have rarely been found in this 

 Order, and neither of two forms, no matter how closely they are evi- 

 dently related can properly be deemed a subspecies, no intermediates 

 having been observed. Also the Author has not seen his way to estab- 

 lish a subspecies between the dweller of an island and one of the main- 

 land, because, no communication being possible, the appearance of 

 intermediates would seem most improbable. Not so however, with the 

 dwellers of contiguous islands which may at one time have been por- 



