[Illustration: FIG. 415.--_Ursus maritimus_, polar bear. Ileo-colic junction. (Columbia University Museum, No. 748.)] [Illustration: FIG. 416.--_Hyaena striata_, striped hyena. Ileo-colic junction and caecum; dried preparation. (Columbia University Museum, No. 56.)] [Illustration: FIG. 417.--_Felis leo_, lion, Ileo-colic junction and caecum. (Columbia University Museum, No. 1516.)] Among the ailuroid carnivora, the hyaena and the lion occupy an isolated position in regard to the caecum. Both of these animals possess a well-developed long caecal pouch with blunt extremity (Figs. 416 and 417). They probably afford examples of a persistent ancestral common type from which the remaining carnivorous forms are derived by reduction of the caecal apparatus in conformity with the food-habits of these animals. The caecum of both the lion and hyaena resembles very closely the pouch of the herbivorous marsupials, such as _Halmaturus_ or _Didelphis_ (cf. Figs. 348 and 350, p. 205). IX. Order: Cheiroptera. In the bats the alimentary canal is uniformly simple without caecum and scarcely any differentiation between small and large intestine (Fig. 418). [Illustration: FIG. 418.--_Pteropus medius_, Indian fruit-bat. Ileo-colon; dried preparation. (Columbia University Museum, No. 533.)] X. Order: Insectivora. In the true Insectivora the caecum is also absent and the alimentary canal a simple non-differentiated tube. In certain herbivorous animals included in this group on the other hand, such as _Galeopithecus_ (Fig. 419), the caecum is present as an enormous sacculated pouch with spiral convolutions. [Illustration: FIG. 419.--_Galeopithecus volans_, colugo. Ileo-colic junction, caecum, and colon. (Columbia University Museum, No. 1844.)] XI. Order: Primates. The caecum is uniformly present. In certain of the Lemuroidea the terminal portion of the pouch is reduced, forming a species of appendix. A typical vermiform appendix is regularly found in man and in the anthropoid apes, orang, gibbon, chimpanzee and gorilla. 1. Suborder Lemuroidea.