ON THE ANATOMY OF PLOTUS LEVAILLANTL. 347 
The proventriculus is composed of two circular areas of deep 
‘glands, which latter are of considerable size and do not come into 
contact, being situated laterally upon opposite sides of the gullet. Page 680. 
These areas are flat, except at their upper margins, where a small 
transverse ridge is developed, which may be the slight foreshadowing 
of the special cavity developed in Plotus anhinga for the reception of. 
the secretion of the gastric glands. But in P. levaillanti it is to be 
noticed that there are two gland-surfaces, whilst in P. anhinga it will 
be remembered there is but one gland-cavity. 
View of the inner surface of the posterior wall of the stomach of Plotus-levaillanti, 
with the cesophagus slit up anteriorly so as to show the whole of its proven- 
tricular surface, with the two gland-areas and the U-shaped elevation on its 
anterior wall (on the left of the figure), as well as the pyloric infundibuliform 
plug. 
The calibre of the esophagus must be somewhat diminished by 
the presence of a curious U-shaped ridge upon the mucous membrane 
of its anterior wall, which is situated between the antero-lateral 
