crania accompanying Morton’s plates, and any thoughtful person cannot avoid surprise that so distinguished a scholar as Agassiz should have committed himself to a theory without first submitting it to a crucial test. That there is a great variety of type observable among the crania figured by Morton, even a superficial examination will show, while a more careful classification presents several facts of interest. For this classification we consider the simple division of the crania into long and short skulls sufficient. The question of other divisions has been often discussed, but with Mr. Huxley we content ourselves with the simplest classification. Referring to a particular instance, he says, “taking the antero-posterior diameter as 100, the transverse diameter varies from 98 or 99 to 62. The number which thus expresses the proportion of the transverse to the longitudinal diameter of the brain-case is called the _cephalic index_. Those people who possess crania with a cephalic index of 80 and above are called _brachycephali_ (short-skulled), those with a lower index are _dolichocephali_ (long-skulled).”[226] Dr. Meigs, while accepting the classification into long and short skulls, admits that it is open to the objection that it forces into either and opposite classes crania closely related to each other in type and measurement.[227] Yet it must be admitted, that in proportion as arbitrary divisions are increased, these difficulties are multiplied, and that this simple, twofold classification presents the fewest.[228] In the following tables, which contain all the measurements accompanying the plates in the _Crania Americana_, the _cephalic index_ is placed in the left-hand column. That a wide difference of type is apparent between the extremes of the dolichocephalic and brachycephalic measurements, certainly cannot be denied.