15 
inch in diameter in the specimen without the gall-bladder. In the larger Struthionide 
the organ generally presents a longer and more compressed figure. 
In considering the physiological relations of the structures which have just been de- 
scribed, we shall be able to trace the same interesting correlation between their different 
modifications and the nature of the organic substances which it is their office to assi- 
milate, as is illustrated in other known and more striking peculiarities in the digestive 
organs of birds. Animals which are destined to subsist exclusively on insects usually 
present the chief prehensile and preparatory parts of the digestive system, whether it be the 
beak, as in the Ibis, or the tongue, as in the Ant-eaters and Woodpecker, of a long and 
slender shape ; in the present species we find a pair of Struthious mandibles lengthened 
out and made slender for this purpose. The beak, thus organized to seize and transmit 
to the gullet objects of small size, is succeeded by a muscular canal of moderate and 
uniform width ; and the food being of an animal nature and swallowed in small quantities, 
with successive intervals, as it is caught, the wsophagus is not required to be modified 
to serve as a reservoir, either by a general width or partial dilatation. The proven- 
triculus of the Aptery« is of a small relative size as compared with that of the Ostrich ; 
its glands are also more simple in their structure, and are not aggregated into a circum- 
scribed mass as in the Rhea, The stomach has its muscular coat more equally but 
less strongly developed than in any of the vegetable-feeding Struthionide ; and the 
small size of the cavity, as well as the moderate strength of its partetes, bespeaks a 
structure adapted for the bruising and chymification of animal substances presenting, 
as do worms and the larvz of insects, a moderate resistance. 
The length of the intestines and the size of the ceca, both of which somewhat exceed 
those in the slender-billed Insectivorous Waders, indicate that the Apteryz—which, by 
being denied the power of flight, is confined to a more restricted range in quest of food 
—is designed to possess every needful and practicable advantage in extracting from its 
low-organized animal diet all the nutriment that it can yield. 
The lacteal absorbents in the Apteryx in which the digestive system before death had 
been actively engaged in the assimilation of a full meal of insects, were plainly visible, 
and in many parts of the mesentery presented an opake white colour. 
There was an absorbent gland, about the size of a hazel-nut, in the mass of fat below 
the root of the neck. 
Circulatory and Respiratory Systems. 
The heart is surrounded by a wide and thin pericardium, which is attached to the 
concave side of the sternum and to the margins of the anterior wide fissure of the dia- 
phragm, through which the ventricular portion of the heart protrudes into the abdomen, 
in the posterior concave interspace of the two great lobes of the liver. (Pl. VL, fig. 1, a.) 
It requires only that a central aponewrosis should have been continued from the anterior 
