The canine teeth of these anthropoids are much worn down by age on their posterior surface. Deep transverse grooves of varying size characterize the teeth of anthropoids, owing to the unequal distribution of the coating of enamel. These are developed with their advancing growth. In addition to these incised furrows, longitudinal marks, with raised edges, also appear, and especially on the anterior surface of the incisor teeth. In the gibbon the anterior surface of the incisor teeth is smooth; in this animal the upper central incisor teeth are the largest, while the lower central incisors are the smallest. The long and strong upper canine teeth, which are laterally compressed, display a sharp posterior angle, and an anterior and inner longitudinal furrow. It has sometimes been said that the grooves found on the external contour of the back teeth of anthropoids, extending to their roots, constitute a not unimportant distinction between their structure and that of the human teeth, in which the grooves do not extend to the roots. But the corresponding human teeth do sometimes exhibit very deep and extensive furrows. I cannot, therefore, ascribe any peculiar significance to this assumed distinction. The development of the canine teeth, like those of beasts of prey, seems to me much more important. A supernumerary back tooth may sometimes be observed both in man and in anthropoids, including also the gibbon.[77] The stomach and intestines of these animals present only a few striking differences from the same organs in man. The length of the intestines varies in man as well as in anthropoids. I have only observed the _valvulæ conniventes_ to be somewhat clearly developed in the gorilla and the orang. The cæcum of these apes is long, broad, placed with the power of free movement in the peritoneum, and furnished, especially in the case of the orang, with a large, very long, and spirally coiled vermiform appendix. The liver is divided into two principal lobes, but in the orang this division is not very clearly marked. I have not myself observed a subdivision of these lobes, occurring on their edges, which is mentioned by Bolau and Auzoux in the case of the gorilla. Bischoff notices in the gorilla the absence of the H-shaped arrangement of the fissures on the under surface of the liver, so noticeable in man; and the same remark applies to other species of anthropoids. Moreover, the fissures on this part of the liver are not incised on the substance with the same uniform depth. The gall-bladder of the gorilla and the orang is not remarkable for its size; in the chimpanzee I found that this organ is large and twisted, and it is also large in the gibbon. The spleen is elongated in the gorilla, chimpanzee, and gibbon, shorter and wider in the orang. On its left contour it is uniformly bevelled off. There is nothing in the pancreas which calls for remark.