This type, which is to be regarded as a further development of the preceding form, is also found in the armadillos. Fig. 359 represents the structures in Dasypus sexcinctus, the six-banded armadillo, and a similar arrangement of the parts exists in Chlamydophorus, another species of armadillo.
Fig. 359.—Dasypus sexcinctus, six-banded armadillo, Ileo-colic junction and cæca. (Columbia University Museum, No. 1478.)
4. The cæcal pouches are more completely differentiated, communicating with the colon by a constricted neck.
This results in an arrangement which recalls the structure of many avian cæca (cf. [Fig. 337]) and is seen in the double cæcal pouches of Cyclothurus didactylus, the little ant-eater (Fig. 360).
Fig. 360.—Cyclothurus didactylus, little ant-eater. Ileo-colic junction and cæca. (Columbia University Museum, No. 1512.)
II. Asymmetrical Type of Ileo-colic Junction.
The second general group of the Edentates is characterized by the gradual development of a single lateral asymmetrical cæcum, in place of the median symmetrical ileo-colic transition found in the forms just considered. The species composing this group thus form a link leading up to the right-angled accession of ileum to large intestine and the lateral cæcum characteristic of most other mammalia.