ANATOMY OF THE THREE-TOED SLOTH. 163 



the transition between the rugose smooth mucosa of the paunch 

 and the hard mucosa of the cardiac stomach. 



The three divisions of the cardiac stomach are separated by 

 partitions, and the septum between the two ventral compart- 

 ments runs for some distance along the inner surface of the 

 paunch (Plate II. B, pin). Microscopic sections of this septum 

 (Plate IV. B) show the transition between the stratified epithelium 

 of the cardiac stomach and the glandular lining of the paunch. 

 The septum between the dorsal and left ventral compartments 

 (Plate II. B, c) is small and strong. The former septum is absent 

 in Cholmpus. The epithelial transition is similar to the junction 

 of the oesophagus and a simple stomach. 



The inner surface of the paxmch is beset with ruga3 whose 

 characters differ on the two sides of the septum running back 

 from the cardiac stomach. On the left side they run in all 

 directions and are mostly small ; on the right side they are 

 mostly large, and pockets are enclosed between them and the 

 gastric wall. One very large septum bisects the caecal appendage; 

 in Plate II. B one of the halves is laid open, and a glass rod 

 passes down through the other one. Between the rugae, which 

 are soft and flabby, the mucosa has innumerable small glandular 

 pits. 



On the right side there are several small, firm ridges passing 

 to the large ridge between the paunch and cardiac stomach, but 

 they are absent on the left side, for the soft mucosa extends right 

 forward to that ridge (Plate II. B, a); and these small ridges are 

 seen above d in Plate II. B. 



The interior of the ccecal appendix has been incompletely 

 described by Rapp (10) and Klinckowstrom (6), and no illus- 

 trations are provided by them. Its inner structure is shown in 

 Plate II. B, and a cross section is diagrammatically represented 

 in text-fig. 12, B. It is ridged by many longitudinal folds, but 

 these are reduced to six in number in the terminal third. The 

 upper two-thirds of the cavity is bisected by a large septum, and 

 small partitions attached to it enclose two pockets on either side. 

 These all open towards the paunch, and the arrows in text- 

 fig. 12 B pass through the two passages on either side of the 

 main septum. 



A prominent muscular ridge (Plate II. B, b) runs from the 

 greater curvature into the left ventral compartment of the 

 cardiac stomach, and ends on the septum between the latter and 

 the dorsal compartment. A second ridge runs from the septum 

 between the two ventral compartments to meet the former ridge, 

 and between them is the opening between the dorsal and left 

 ventral compartments of the cardiac stomach. 



The oesophagus is continued right into the pylorus by a groove 

 running through the left ventral and dorsal compartments of the 

 stomach. It is shown in Plate III. A, a, and its characters are 

 the same as those already described by Rapp and Klinckowstrom. 



The pyloric region, which is U-shaped, has dorsal glandular 



II* 



