This classification, also, is liable to many objections. Like Camper's, it left out several important characteristics. _Owen_ supposed that these objections might be obviated by measuring the basis of the skull instead of the summit. "The relative proportions and extent," says Prichard, "and the peculiarities of formation of the different parts of the cranium, are more fully discovered by this mode of comparison, than by any other." One of the most important results of this method was the discovery of a line of demarcation between man and the anthropoid apes, so distinct, and clearly drawn, that it becomes thenceforward impossible to find between the two genera the connecting link which Camper supposed to exist. It is, indeed, sufficient to cast one glance at the bases of two skulls, one human, and the other that of an orang, to perceive essential and decisive differences. The antero-posterior diameter of the basis of the skull is, in the orang, very much longer than in man. The zygoma is situated in the middle region of the skull, instead of being included, as in all races of men, and even human idiots, in the anterior half of the basis cranii; and it occupies in the basis just one-third part of the entire length of its diameter. Moreover, the position of the great occipital foramen is very different in the two skulls; and this feature is very important, on account of its relations to the general character of structure, and its influence on the habits of the whole being. This foramen, in the human head, is very near the middle of the basis of the skull, or, rather, it is situated immediately behind the middle transverse diameter; while, in the adult chimpantsi, it is placed in the middle of the posterior third part of the basis cranii.[125] Owen certainly deserves great credit for his observations, but I should prefer the most recent, as well as ingenious, of cranioscopic systems, that of the learned American, Dr. Morton, which has been adopted by Mr. Carus.[126] The substance of this theory is, that individuals are superior in intellect in proportion as their skulls are larger.[127] Taking this as the general rule, Dr. Morton and Mr. Carus proceed thereby to demonstrate the difference of races. The question to be decided is, whether all types of the human race have the same craniological development. To elucidate this fact, Dr. Morton took a certain number of skulls, belonging to the four principal human families--Whites, Mongolians, Negroes, and North American Indians--and, after carefully closing every aperture, except the _foramen magnum_, he measured their capacity by filling them with well dried grains of pepper. The results of this measurement are exhibited in the subjoined table.[128]