[Illustration: FIG. 387.--_Lepus cuniculus_, rabbit. Ileo-colic junction with saccus lymphaticus. Caecum and proximal segment of colon opened to show spiral mucous fold in interior. (Columbia University Museum, No. 1587.)] [Illustration: FIG. 388.--_Lepus cuniculus_, rabbit. Caecum and appendix inverted to show spiral fold and structure of mucosa. (Columbia University Museum, No. 1588.)] The coils of the proximal colon encountered in many rodents are well seen in _Dasyprocta agouti_, the agouti (Figs. 389 and 390), which animal also illustrates a type of caecum found in several members of the order. The pouch here is large, sacculated, uncinate, without reduction of the terminal portion. [Illustration: FIG. 389.--_Dasyprocta agouti_, agouti. Ileo-colic junction, caecum, and colon. (Columbia University Museum, No. 24/1576.)] [Illustration: FIG. 390.--_Dasyprocta agouti_, agouti. Ileo-colic junction, caecum, and colon. (Drawing based on preparation shown in Fig. 388.)] [Illustration: FIG. 391.--_Lagomys pusillus._ Ileo-colic junction, caecum, and colon. (After Pallas, from Oppel, "Lehrbuch d. Vergl. mikrosk. Anat. d. Wirbelthiere," II., Jena, 1897, p. 577, Fig. 314.)] [Illustration: FIG. 392.--_Arvicola pennsylvanicus_, field mouse. Alimentary canal. (Columbia University Museum, No. 815.)] [Illustration: FIG. 393.--_Mus decumanus_, white rat. Ileo-colic junction, caecum, and colon. (Columbia University Museum, No. 1574.)] The relatively enormous size of the caecum in the _Muridae_ is shown in Fig. 392, representing the entire visceral tract of _Arvicola pennsylvanicus_, the meadow mouse. The pouch in these animals is large, smooth and of uniform caliber (Fig. 393). In some the colon beyond the entrance of the small intestine is provided with a spiral mucous valve (Fig. 394). [Illustration: FIG. 394.--_Arvicola riparius_, meadow mouse. Ileo-colic junction, caecum, and colon. (Columbia University, Study Collection.)] In the single instance of _Myoxus_ among the rodents, the ileo-colic junction is simple, without any caecal pouch (Fig. 380). VIII. Order: Carnivora. A. PINNIPEDIA.--In the seals and walrus the caecum is very small with a blunt termination. Fig. 395 shows its structure in _Zalophus gillespiei_, Gillespie's sea-lion, and Fig. 396 in _Phoca vitulina_, the harbor seal. [Illustration: FIG. 395.--_Zalophus gillespiei_, Gillespie's sea-lion. Ileo-colic junction and caecum; dried preparation. (Columbia University Museum, No. 90.)] [Illustration: FIG. 396.--_Phoca vitulina_, harbor seal. Ileo-colic junction and caecum. (Columbia University Museum, No. 762.)] B. FISSIPEDIA.--The _Cynoidea_, including the dogs, jackals, wolves and foxes, form a well-marked central group with well-developed convoluted caeca placed laterally to the ileo-colic junction (Figs. 397-399). [Illustration: FIG. 397.--_Vulpes fulvus_, red fox. Ileo-colic junction and caecum; dried preparation. (Columbia University Museum, No. 114.)]