In some the colon beyond the entrance of the small intestine is provided with a spiral mucous valve (Fig. 394).

Fig. 394.—Arvicola riparius, meadow mouse. Ileo-colic junction, cæcum, and colon. (Columbia University, Study Collection.)

In the single instance of Myoxus among the rodents, the ileo-colic junction is simple, without any cæcal pouch ([Fig. 380]).

VIII. Order: Carnivora.

A. Pinnipedia.—In the seals and walrus the cæcum 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.

Fig. 395.—Zalophus gillespiei, Gillespie’s sea-lion. Ileo-colic junctionand cæcum; dried preparation. (Columbia University Museum, No. 90.)

 

Fig. 396.—Phoca vitulina, harbor seal. Ileo-colic junction and cæcum.(Columbia University Museum, No. 762.)

Fig. 397.—Vulpes fulvus, red fox. Ileo-colic junction and cæcum; driedpreparation. (Columbia University Museum, No. 114.)

B. Fissipedia.—The Cynoidea, including the dogs, jackals, wolves and foxes, form a well-marked central group with well-developed convoluted cæca placed laterally to the ileo-colic junction (Figs. 397-399).

Fig. 398.—Canis familiaris, dog. Ileo-colic junction and cæcum, Type I. (Columbia University Museum, No. 1550.)   Fig. 399.—Canis familiaris, dog. Ileo-colic junction and cæcum, Type II. (Columbia University Museum, No. 1551.)