342 MR. A. H. GARROD ON THE f^i )r - ^ > 



termination of the oesophagus, the epithelium in that part being quite 

 smooth and apparently squamous. 



This further development in Plotus of a special and well- differen- 

 tiated gland-organ from what in other hirds is a zone or a simple 

 circular patch of glands, is very similar to the equally uncommon 

 development of the cardiac gland-organ in the stomach of the 

 Manatee, which is most certainly only a modification of the similarly 

 situated gland-patch in the Dugong. 



The stomach is not developed into a gizzard, its walls in no part 

 exceeding one sixth of an inch in thickness. It is divided into two 

 compartments, a cardiac and a pyloric, as is that of the Pelican. 

 The former of these corresponds to the gizzard in most birds, the 

 latter to the imperfectly formed cavity associated with the pyloric 

 valve in the Storks, Gannet, &c. (vide Plate XXVIII. fig. 2). 



Of the stomach of the Pelican, Hunter tells us* that " it is oblong, 

 much in the direction of the oesophagus, with a little curve, smallest 

 at the lower end : it makes a quick turn and swells again into a 

 round bag ; or it may be supposed that from the side near the 

 lower or smaller end is attached a bag whence the duodenum arises." 

 In the Catalogue of the Museum of the Royal College of Surgeons 

 (1852), Prof. Owent remarks, with reference to a specimen (No. 519) 

 of the stomach of a Pelican (Pelecanus onocrotalus), " The oeso- 

 phagus is continued into the proventriculus or glandular cavity, 

 without any marked constriction ; and the latter passes insensibly 

 into the part analogous to a gizzard. This part communicates by a 

 transverse aperture with a small globular cavity, which is lined by a 

 vascular membrane, and communicates with the duodenum by a very 

 small oblique aperture. This superadded cavity renders the analogy 

 between this stomach and that of the Crocodile complete, with the 

 exception of the absence in the latter of distinctly developed gastric 

 glands. These, in the Pelican, are simple elongated follicles, closely 

 compacted together, and extended over a large surface." In Plotus 

 the second cavity is similarly situated, intervening between the 

 stomach proper and the duodenum. The dense yellow epithelium 

 of the one, however, extends into the other, right up to the pyloric 

 valve. [It may be that in the specimen described by Prof. Owen 

 the lining had been previously stripped off, which may have led to 

 the term vascular being applied to the mucous membrane of the 

 second stomach.] 



Hunter, in his dissection of Siila and Phalacrocorax, does not 

 mention the existence of a second stomach ; and I have not observed 

 or found recorded such an arrangement in either of those genera, 

 or in Phaethon, or in Fregata. 



In Plotus there is still another peculiarity which, as far as I know, 

 is found in only one other bird, namely Cathartes aura. In Audu- 

 bon's ' Ornithological Biography ' %, Mr. Macgillivray tells us that 

 in the stomach of C. aura " there is a pyloric lobe [second com- 



* Essays and Observations, Own'? edition, 1861. 

 t Vol. i. ''Organs of Motion and Digestion," p. 148. 

 J Vol. v. p. 340. 



