228 ELEMENTS OF ORNITHOLOGY, 
The epiotic is superior and posterior, and shelters the posterior 
semicircular canal. 
The two latter bones anchylose with the occipitals next to 
them behind, before they anchylose with the ‘“ prootic.” 
The earlier condition of the limb-bones of birds serves to 
reveal their essential composition. Then we find the four 
carpal * bones and all the three metacarpal bones distinct. 
Similarly in the leg we find the two tarsal elements distinct 
which in adult life respectively anchylose with the distal end of 
the tibia f and the proximal end of the tarso-metatarsal, and the 
last-named bone plainly shows how it is made up not only of a 
tarsal element, but of three metatarsals also. 
The wonderful egg-laying capacity of the domestic Fowl is 
notorious both for its duration and the number laid in a nest. 
Wild Birds of the Fowl and Pheasant kind will also lay a con- 
siderable number of eggs. Many small Birds lay and sit on 
eight or ten eggs, and many Birds lay only five or six. Pigeons 
lay but two, and the same is the case with Humming-birds, 
while the Petrel and the Penguin lay but one. 
The size of the egg is not strictly related to the size of the 
individual which lays it. Thus the Apteryx, though only about 
as large as a moderately sized Fowl, lays a very large egg. 
The Guillemot and the Raven are Birds of about the same size, 
but the egg of one is ten times the size of that of the other, 
that of the Guillemot being as big as that of an Eagle. 
The shapes of eggs also differ considerably. Thus those of 
the Owls are nearly round, while those of the Heron and Sand- 
grouse are elongated with both ends nearly equal in size. 
Everyone knows, on the other hand, that the Plover’s egg is 
pear-shaped, and some of the Guillemots lay eggs which 
attenuate very rapidly towards the smaller end. In the Grebes 
the eggs are pointed at both ends, although very wide in the 
middle. 
The grain of the shell is different in different species. It is 
* Probably answering to the magnum and unciform bones of man and 
beasts, as well as the scapho-lunar and cuneiform bones. There is also 
sometimes a fifth carpal ossicle, which afterwards anchyloses with the 
metacarpus, as also do the representatives of the magnum and uneiforme. 
It has been termed the pentosteon. 
+ This proximal element consists at first of two distinct parts, which, as 
they lie beneath the ends of the two leg-bones, may be distinguished as the 
tibiale and the fibulare respectively. 
