Here are presented three different dilatations, the first probably congenitally started and aided by pulmonary fibrosis, therefore secondarily a traction diverticulum, the second probably entirely congenital, and the unusual third case due to obstruction by an enlarged thyroid. In this connection might be mentioned small saccular diverticula in the proventricle of a Fire Finch (_Lagonosticta senegala_), and at the pylorus in a Puma (_Felis concolor_). Neither of these seemed of any significance and played no part in the death of the animals; they did not seem to be artificially produced, by worms, for example. THE PROVENTRICLE. The proventricle or forestomach of birds, is the seat of active secretion of the gastric juice in nearly all orders, although Jobert believes that the mucosa of the gizzard may contribute some digestive fluid, and there are active glands in this tissue in a few orders. The proventricle does not act as a reservoir during digestion, but as soon as the juices are well mixed with the bolus the food is passed on to the gizzard. The organ has a rather free position, at least as far as its left lateral and downward movements are concerned for the left lateral abdominal air sac is free on that side of the gastric complex and the left lateral thoracic also extends down the side of the proventricle. Upward and anteriorly is the heart. Some of the cases of proventricular spiropteriasis have shown very marked congestion of the left lung, possibly due to the closure of the anteroinferior air sac aperture on that side. Aside from parasitism, affections of this organ are not very numerous. Infestation with spiroptera and with less dangerous worms was quite serious at one time, but since routine examinations of all suspicious birds has been practiced this parasitism has been under control. This is a subject of especial importance to collections, and will be described in a special section. The susceptibility of the proventricle to damage seems from our figures to be very distinctly a matter of zoological order. In so far as parasites are concerned, the parrot group stands away ahead of all others having an incidence among autopsies upon Psittaci of 16 per cent.; after them come the Picariæ with 9 per cent., and Columbæ and Passeres each with 4 per cent. When, however, non- verminous conditions are reviewed the anserine birds are found the most susceptible, 3 per cent. of the autopsies upon this order revealing proventricular lesions; after them come the Columbæ, 2 per cent., and Psittaci, 1.5 per cent. In this group are included inflammations of all kinds, dilatations and distentions and some lesser matters.