736 NATURAL HISTORY MISCELLANY. 
morphological development the animal was two stages below the 
youngest described embryo of the lowest kind of fish, but one. 
The larva of the lamprey was the earliest condition of a fish’s 
skull with which we are acquainted. He had succeeded in getting 
two stages below the larva of the lamprey. From this stage he 
had worked up the development of the frog until he came to the 
tadpole, which is the representation of the types of rays and 
sharks. As he ascended in the various stages the likeness to the 
other vertebrata became very apparent. In an adult frog (Rana 
temporaria) he had obtained a metamorphic development of such 
height that it bordered upon our own class,the Mammalia. At the 
same time it should be stated that other parts of that frog’s skull 
retained the simplicity of the adult lamprey. In the frog we had a 
creature who had run across the whole circle of types, creeping grad- 
ually up to the Mammalia and yet never losing his relation to the 
original type, but retaining its structure and relation to the very 
end, although subdividing and metamorphosing certain of the facial 
arches into the very number of parts that we have in our own 
inner ear. The chain of bones in the human ear (the hammer, 
the anvil, the round bone and the stirrup) had caused a great deal 
of trouble to anatomists in their attempts to trace the series of 
metamorphic changes. He had, however, made this clear by trac- 
ing the history of the facial bones of a frog, a creature which was 
but a fish in respect of its earliest embryonic conditions. Suppos- 
ing the doctrine of development to be true, it would seem that we 
ourselves have come originally in some line sub-parallel to the frog 
(he would not say from the frog itself, although man had repeated 
the form tail-less). Even in the highest oviparous vertebrates no 
sub-division of a facial bar to form that tiny but really important 
part of the human skull, the os orbiculare, ever obtained. In 
this respect the frog comes nearer to the Mammalia than any bird. 
Birds have branched out in a direction quite away from the ordi- 
nary line, and have culminated in their own glorious types. If it 
is desired to trace the development of the Mammalia, inquiries 
must commence with the Batrachia, and in such inquiries the 
thought constantly occurs that between us and the Batrachia there 
have been lost whole groups of creatures. We were only just be- 
ginning to see the manner in which the work ‘of tracing the devel- 
opment of the higher forms of animal life was to be carried on. 
—From Address of H. W. Parker, before the Royal Microscopical 
Society, in the Monthly Microscopical Journal. 
