One cannot speak so definitely of pleuritis in birds since this tissue merely represents in them the covering of the lung and is firmly attached posteriorly to the ribs and anteriorly to the air sacs. Exudates show as collections upon the air sac side of the combined membrane, pleuritis proper in birds being an infiltrative affair coming through the pulmonary tissue and therefore being a part of pneumonitis. I notice a tendency in a few articles to write of pleuritis when the process is confined to the thorax but this gives the impression that the disease is peculiar. There seems no difference in the gross and minute appearance between thoracic serositis and panserositis. The course of procedure seems to be from the anterior or mesial pulmonary ostia into respectively the cervical and thoracic air sacs and this seems to hold good whether the infection be mycosis or fowl cholera or fowl pest. There are records of 104 cases of serositis in birds of which 45 were among parrots, the remainder being well distributed among the various orders; only two each occurred in Galli and Anseres, orders prominently affected under domestication. This high percentage of pleuroperitonitis among parrots and their congeners can only be explained upon the ground of a continued infection of our stock by the virus of fowl cholera and by mould. One case of undoubted fowl cholera occurred recently and as the records are reviewed a few are discovered where the organism was found. The virus must be of low grade for we have had no severe and devasting epizoötic. Mycosis is constantly with us no matter what we do in hygienic measures. There was a small group of cases of pulmonary and serous membrane mycosis combined with staphylococcus infection which carried off six birds. The pathology of this group was interesting because one could follow the infection of the bacterium. The anterior pulmonary ostium was surrounded or covered by a mycotic mass and spreading downward from this was a grayish yellow turbidity of the air sac walls with a delicate sticky or almost mucilaginous exudate extending into the lateral abdominal and posterior sacs. [Illustration: FIG. 12.—ENDOTHELIOMA OF PLEURA. LEOPARD (FELIS NEBULOSA). ] [Illustration: FIG. 13.—ENDOTHELIOMA OF PLEURA IN FIG. 12. DETAIL OF ONE OF THE WARTY EXCRESCENCES. ] There is on record one tumor of the pleura, an endothelioma, in a Clouded Leopard (_Felis nebulosa_). It was the usual plate-like thickening with warty excrescences. No metastases occurred. (Figs. 12 and 13). SECTION VII THE ALIMENTARY TRACT. PART 1.—PHARYNX, ESOPHAGUS, STOMACH AND INTESTINES