XL] THE ALIMENTARY SYSTEM. 443 



Nothing like a crop exists in man's class, with the single 

 exception of the common Dormouse, which has the lower 

 end of the oesophagus enlarged into a glandular dilatation. 



The oesophagus may be much more muscular than in 

 man; or it may be rather valvular at its lower end, as in 

 the Dugong, and still more so as in the Porpoise. 



The stomach is sometimes indistinguishable from the 

 oesophagus, with which it is directly continuous, without any 

 marked constriction, as in most Fishes. It may form one 

 continuous canal with the oesophagus, even in Birds, e.g. the 

 Cormorant ; and indeed in Birds (Fig. 378, pr\ generally the 

 first or cardiac part of the stomach (called the proventriculus] 

 seems to resemble more a dilatation of the lower end of the 

 oesophagus like that of the Dormouse than a stomach 

 proper. 



It may attain to a very much greater complexity than it 

 attains in man, as we see by the Sheep. 



The various exaggerated forms which the stomach assumes 

 may be arranged under two heads : (i) an elongation, (2) a 

 differentiation, with distinct correlated chambers. 



The first condition may exist even in man's own order, as 

 in the long-tailed Monkeys of India, the Semnopitheci, 

 which have the pyloric part of the stomach exceedingly 

 elongated and also sacculated, i.e. puckered up into a succes- 

 sive series of bags. This condition is carried still further in 

 the Kangaroo, where the cardiac end is also exceedingly 

 prolonged. 



The second form of stomach is slightly exemplified in the 

 Pig, where the cardiac fundus is dilated into a little pouch, 



FIG. 375. STOMACH OF A SHEEP, cut open to show the various lining of the 



different parts. 



ce, oesophagus ; r, rumen or paunch ; rt, reticulum or honeycomb ; ps, psaherium 

 or manyplies ; a, abpmasum or rennet : d, duodenum. 



while two parallel folds lead from the oesophagus to the 

 pylorus. In the Sheep, however, we find the cardiac end 



