[Illustration: FIG. 456.--Drawn from same preparation as Fig. 455; view from left side, showing formation of posterior ileo-caecal fossa.] [Illustration: FIG. 457.--_Gorilla savagei_, gorilla. Ileo-colic junction and caecum, with ileo-caecal folds. (Drawn from Columbia University Museum preparation No. 1543.)] (For arrangement of the ileo-caecal folds and fossae in this form see p. 269.) =2. Gorilla savagei, Gorilla= (Fig. 457).--The caecum is large, distinctly sacculated, presenting a decided curve with the concavity directed toward the left. The appendix is implanted at the center of the blunt apex of the pouch, the caecal sacculations on each side of the root of the appendix being of nearly equal size (folds and fossae, cf. p. 269). [Illustration: FIG. 458.--_Simia satyrus_, orang. Caecum and ileo-colic junction; ventral view. (Drawn from Columbia University Museum preparation No. 716.) 1. Appendix. 2. Ventral vascular fold.] [Illustration: FIG. 459.--_Simia satyrus_, orang. Caecum and ileo-colic junction; dorsal view. (Drawn from Columbia University Museum preparation No. 716). 1. Appendix. 2. Intermediate non-vascular fold.] =3. Simia satyrus, Orang-outang.=--Figs. 458 and 459 represent respectively the ventral and dorsal views of the caecum and ileo-colon in a nearly adult male specimen of orang, about 41/2 feet high. The caecum is funnel-shaped, gradually narrowing to the origin of the appendix from its apex, which is carried upwards to the left by the well-marked crescentic curve of the pouch. The sweep of the funnel to the left and upwards is characterized by the curved course of the ventral longitudinal muscular band (Fig. 458), whose fibers spread out over a surface 3 cm. wide. The apex is thus placed behind the terminal ileum close to its entrance into the large intestine. At the level of the upper margin of the ileo-colic junction the narrow pointed termination of the caecum passes gradually into the beginning of the appendix (Fig. 459). The appendix measures along its free border 22.6 cm. It follows the direction of the caecal curve for 2.7 cm., at which point it appears somewhat constricted and takes an abrupt bend downwards for 4.3 cm.; curving again upwards for 7.5 cm., it turns downward a second time for 5.4 cm. and terminates in a hook-like extremity 2.7 cm. long (Fig. 459). [Illustration: FIG. 460.--_Troglodytes niger_, chimpanzee. Ileo-colic junction and caecum; ventral view. (Drawn from Columbia University Museum preparation No. 675.) 1. Appendix. 2. Intermediate non-vascular ileo-caecal fold. 3. Colon.] [Illustration: FIG. 461.--_Troglodytes niger_, chimpanzee. Dorsal view. (Drawn from Columbia University Museum preparation No. 675.) 1. Appendix. 2. Intermediate non-vascular ileo-caecal fold. 3. Dorsal vascular fold.] =4. Chimpanzee, Troglodytes niger.=--Figs. 460 and 461 represent the ventral and dorsal view respectively of the caecum and ileo-colon in a young specimen.