ON THE ANATOMY OF PLOTUS ANHINGA. Bag 
Hunter, in his dissection of Sula and Phalacrocoraz, 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 
Phaéthon, 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 Audubon’s 
“ Ornithological Biography,”* Mr. Macgillivray tells us that in the 
stomach of OC. aura “there is a pyloric lobe [second compartment] Page 343. 
about half an inch in diameter, which is lined with bristly hairs. 
They are all inserted at right angles to the surface, penetrate to the base 
of the epithelium, and are of various lengths, some of them not pro- 
truding beyond the surface, others upwards of half an inch, of various 
colours, some black, generally tipped with whitish, others light 
greyish yellow, all thick at the base, and tapering to a fine point. 
Being disposed in a regular manner, they might seem to form a part 
of the organization of the stomach, and not to be, like the hairs found 
in Cuculus canorus and Coccyzus americanus, merely extraneous.” 
The pyloric orifice in Plotus anhinga, as is seen in Plate [20] XXVIII. 
fig. 2, is protected by a mat of lengthy hair-like processes, much like 
cocoa-nut fibre, which nearly half fills the second stomach. This 
second stomach is globose, and nearly an inch in external diameter. 
Its dense lining-membrane is raised into short ruge and tubercles, as 
_ is that of the first; and it is evidently a modification of the epithelium 
which develops these tubercles in the region of the pylorus which 
gives rise to the above-mentioned mat-sieve. The hairs composing the 
mat are hispid, slender, and about half an inch long. They arise 
from a surface a little less than a square inch in area round the 
pylorus, which is in its centre. They cease at the very margin of the 
small circular orifice, where the commencement of the delicate mucous 
membrane of the duodenum can be just seen. My friend, Mr. E. A. 
Schafer, Assistant Professor of Physiology at University College, has 
very kindly examined these hairs microscopically, and tells me that 
*‘they are much more like true hairs, both in structure and mode of 
attachment, than they are like the epithelial projections which are so 
often met with over the filiform papille of the human tongue, which, 
at first sight, they much resemble. Like hairs, they consist of an 
outer ‘cuticular’ part, and an inner ‘fibrous’ part; and in some places 
there is also yet another substance running along the middle of the 
fibrous part, which might be compared to the medulla of a hair. The 
cuticular part is much thicker in proportion than that of a cutaneous 
hair, and forms here and there dentate projections at the sides of the 
filament. The cuticle is continuous with the horny superficial portion 
* Vol. v. p. 340. 
