Impaction of the mammalian stomach is a diagnosis made but once in our records, an Indian Antelope (_Antilope cervicapra_), and this is viewed with suspicion. The rumen was undoubtedly tightly packed, being distended to its fullest capacity with rather dry and not properly softened grain. However, postmortem changes had advanced and therefore observations in the whole body were not dependable. The bulk of food which can be accommodated by the rumen is very large, and had this not been dry and firm the condition might not have been interpreted so seriously. Many animals come to autopsy with a well filled, indeed even with a well packed stomach, but there is usually sufficient reason for this or there is distinct pathology to account for death. All this of course implies a stomach of normal or approximately normal dimensions since distention beyond this, or dilatation of the stomach, is more definite. In veterinary medicine, gastric tympanites (rumen alone or all stomachs, or the simple stomach) is ascribed to food that ferments easily when taken in excess or in the presence of defective motor power, to constrictions by scars and to obstructive tumors; excessive feeding is sometimes mentioned but given a subordinate rôle. Our records throw very little light upon the subject since only five cases were observed. Four of these five seem to be due to acute fermentation independent of gross physical obstruction, while one, a Cape Hunting Dog (_Lycaon pictus_) showed an old chronic ulcerative gastritis with both healed and active ulcers distorting the pyloric end of the organ. Three of the first mentioned four were monkeys and one was an ocelot. The stomach of the voracious monkey is at time of dissection usually well filled, but in these cases there seems no doubt that gas and excess fluid had distended the cavity enormously, in one instance apparently assisting in acute cardiac dilatation. There were no obvious reasons for assuming any damage to the gastric motor mechanism. [Illustration: FIG. 15.—ROUND ULCERS IN STOMACH WALL. COMMON OPOSSUM (DIDELPHYS VIRGINIANUS). THERE IS GENERAL MODERATE CHRONIC GASTRITIS WITH ROUND ULCERS NEAR THE CARDIA. ] GASTRIC ULCERS.