ON THE ANATOMY OF PLOTUS ANHINGA. 3845 
The large intestine is 6 inches long in the female, and 3 inches in the 
male. There is only a single cecum, exactly like that in the Ardeide, 
in my specimens. This conformation of cecum is found in no other 
Steganopod bird, there being two ceca in all the other genera. These, 
in Pelecanus, are a little over an inch in length, in Sula slightly 
shorter, whilst in Phalacrocoraz, Fregata, and Phaéthon they are simple 
knob-like bodies, nearly globose in form. The rudiment of the 
vitelline duct is persistent. 
In the distance of its diminutive cecum from the cloaca (in other 
words, in the length of the large intestine) Plotus differs slightly from 
its allies. In Pelecanus the large intestine is under 2 inches in 
length ; and it is much the same in Sula. In Phaéthon it does not 
exceed a quarter of an inch in length. It, however, differs consider- 
ably in my two specimens, being in both longer than the same in 
Audubon’s specimen. 
In the urino-genital system of Plotus anhinga, in both sexes, the 
ducts open in the normal manner into the cloaca, just above its lower 
orifice. This orifice, however, is not on the surface, but is into a 
cavity, behind the cloaca, which opens externally quite close to the 
place where the two communicate. Except for this nearly marginal 
orifice the second cavity is a cecal sac, oval in shape, and about 13 inch Page 345. 
high, covered at its blind end with the crypts of shallow glands, which 
also run down its sides. That it is a modification of the bursa Fabricit 
cannot be doubted. 
EXPLANATION OF PHE PLATES. 
Piate 18. (XXVLI) 
Fig. 1. View of left side of neck of Plotus anhinga, dissected. l1.c.a. longus colli 
anterior muscle; /.c.p. longus colli posterior muscle. The fibrous repre- 
sentative of Donitz’s bridge is seen attached to the ninth cervical vertebra. 
2. View of part of the posterior region of the neck of Plotus anhinga. The 
roman figures refer to the cervical vertebre counted from the head. 
Donitz’s bridge is seen attached to the ninth; and at @ is also seena 
fibrous band, which is of similar function, attached to the eleventh. At 
4 is seen the fasciculus of the tendon of the posterior neck-muscle which 
traverses the fibrous loop, which latter has been removed on the left side. 
Pirate 19. (XXVILI.) 
¢ View of the anterior thoracic region of Plotus anhinga, dissected to show the 
superficial (p. 1, 1) and deep layer (p. 1, 2) of the pectoralis major muscle 
on the right side, as well as the pectoralis minor (p. 2) on the left. The 
insertion of the deeper layer of the pectoralis major is seen to be sur- 
rounded by the much more considerable mass of the similar portion of the 
superficial stronger layer. The triceps (4) and the biceps (4) of the cubitus 
are seen on the right side, as in the patagial slip (4.s) of the latter. The 
