516 REPORT OF NATIONAL MUSEUM, 1888. 



and Art, Edinburgh, and another has been sent in exchange to the 

 Australian Museum, Sydney, New South Wales. Two skeletons are 

 retained for the reserve series, U. S. National Museum, and three or 

 four less complete can still be made up from the bones remaining, while 

 there is besides a large number of individual bones, good, bad, and 

 indifferent, left for study. 



This wealth of material has offered an unusual opportunity for the 

 study of individual variation, and it is hoped that the following notes 

 may be of some interest in connection with that most interesting i)rob- 

 lem. 



Unfortunately the conditions under which the remains were found 

 limited all comparisons to individual bones, the inextricably mixed 

 state ot the skeletons precluding all possibility of comparing them with 

 one another in their entirety. 



Variations are of degree or of kind, due to modifications of develop- 

 ment or of structure, and the importance of any departure from a given 

 type depends very largely on the answer to the question to which of 

 these two categories does the variation belong. Moreover, in consider- 

 ing the variations of any one species the variations of the group to 

 which that species belongs must be taken into consideration also, as 

 well as the liability to modification of each and every part. 



Differences of size, unless excessive, are of little value, provided the 

 parts preserve their relative proportions, and in judging of differences 

 in proportion the age of the individual must be taken into account. 

 This fact was very strongly impressed upon the writer many years ago 

 by the study of an extensive series of skulls of the Orang, represent- 

 ing individuals of all ages, and Mr. J. A. Allen has noted similar dif- 

 ferences, due to age, in skulls of the spider monkey. 



The examination of some considerable series of skeletons of various 

 animals has confirmed my belief in the existence of a large amount of 

 individual variation, while at the same time creating an equal belief 

 that, as a rule, the difference between specific and individual variation 

 is readily recognizable. 



In the present case the amount of variation is no more than might 

 be expected to be found in any large bird were an equal series of bones 

 examined. The skulls in particular present a striking similarity not 

 only in shape but in size, and of seventeen crania ten have exactly 

 the same parietal breadth, while the largest differs from the smallest 

 by little more than 6'"''', a difference that must be considered trivial 

 when the size of the skull is taken into account. Moreover, this vari- 

 ation is due to two skulls, one of which is unusally large, while the other 

 is equally small. 



By far the largest skull on record is one collected by Professor Milne 

 and now in the museum of the University of Cambridge, England. The 

 measurements of this specimen appear in the table given farther on. 



The shape of the foramen magnum and the number of perforations 



