Virchow and W. Gruber have agreed in representing this frontal process as theromorphological--that is, as a characteristic of the lower animals, and more especially of apes. Virchow has found this abnormal formation of the skull to be more common in some races than others. None of those in whom it occurs appear to belong to the Aryan races, and the existence of this process and stenocrotaphy, or temporal stenosis, seem to be due to a defective development of the greater wing of the sphenoid bone, and to the compression of the bones in its vicinity, by which the whole temporal region is contracted. This is a characteristic of the lower, but by no means of the lowest, races of men. Stieda, Hyrtl, Gruber, and Calori have sought to controvert the fact that this temporal process is a characteristic of the lower races. Stieda asserts that it may occur exceptionally in all races of men.[31] He himself, aided by Anutschin, has ascertained the existence of this anomalous pterion on more than 10,000 human skulls, and he has also received information from others. He considers the frequency of this frontal process in man to be theromorphological, or indeed pithecoid. According to Anutschin, this anomalous condition is not equally common in all races. In the dark-skinned and woolly-haired races (Australians, Papuans, and negroes) the frontal process is most widely diffused; it is less frequent among Mongolians and Malays; and among Americans and white men its occurrence is from five to six times more uncommon than in the black races. Sometimes the frontal process occurs on the intercalary bone (_Ossa epipterica_), which is fused into the squamous portion of the temporal bone; and sometimes the process grows out of the squamous portion of the temporal bone. These imperfect processes or intercalary bones are not regarded by Anutschin as pithecoid, since they are more rare in apes than in men. Schlocker has sought to show that the frontal process of the squamous portion of the temporal bone, the less common temporal process of the frontal bone, and the temporal intercalary bone (_Ossa epipterica_) are of equal value from the genetic point of view.[32] This author regards the frontal process and the immediate connection of the frontal and squamous portion of the temporal bones, as theromorphological characteristics, but he does not believe the occurrence of this process to be restricted to the lower races.[33] This is also the opinion of Ten Kate. However this may be, the establishment of this theromorphological formation is important. Its immediate value as a contribution to the theory of the origin of species remains, as we shall presently see, even if we cannot trace it through intermediate and lower types.