Aug., 1891. 
ANIMAL PEDIGREES. 
179 
Embryology is not to be regarded as a master-key that 
will open the gates of knowledge, and remove all obstacles 
from our path without further trouble on our part ; it is 
rather to be viewed and treated as a delicate and complicated 
instrument, the proper handling of which requires the 
utmost nicety of balance and adjustment, and which unless 
employed with the greatest skill and judgment may yield 
false instead of true results. 
We are, indeed, only just beginning to understand the 
real power of our weapons and the right way of employing 
them; and in the future embryology, especially when studied, 
as it should be, in conjunction with palaeontology, may be con¬ 
fidently relied on to afford a far clearer insight than we have 
yet obtained into the history of life on the earth. 
Description of the Figures. 
Figs. 1 to 4.—Shells of Peneroplis and of Orbitolites, members 
of the group of Porcellanous Foraminifera, illustrating the mode of 
transition from the spiral to the discoidal shell. (After Brady and 
Carpenter.) 
Fig. 1.—An adult Peneroplis shell. The shell is spiral and 
chambered, the later formed chambers beiug very wide, and having a 
tendency to overlap the preceding ones. X 20. 
Fig. 2.—A young Orbitolites shell, in the Peneroplis stage of 
development. The shell is spiral and chambered, the last formed 
chambers having a more marked tendency to overlap the preceding 
ones than in Peneroplis. The last or marginal chamber in the 
specimen figured extends almost the whole way round. x 30. 
Fig. 3.—An adult Orbitolites shell, seen edgeways so as to show 
the thickness of the disc, and the marginal pores through which the 
pseudopodia are protruded during life. X 7. 
Fig. 4.—An adult Orbitolites shell, seen full face. In the centre 
is the spiral nucleus, which is the oldest part of the shell, and was 
originally the only part present ; then comes a part in which the 
successive chambers become wider and wider, and overlap the older 
part of the shell more and more completely (compare Fig. 2), and 
finally the marginal and latest formed part in which each chamber 
is circular and completely surrounds its predecessors. 
The fainter radial lines indicate the secondary partitions by 
which the chambers are subdivided. X 7. 
Figs. 5 to 7.—Young and adult specimens of the Flounder 
(Pleuronectes flesus), to illustrate the shifting of the eye from one 
side of the head to the other during the growth of the fish. 
Fig. 5.—A young Flounder six days after hatching. The head 
is symmetrical, and the eyes one on each side. (After Cunningham.) 
x 4. 
Fig. 6.—A young Flounder, probably about a month old. The 
fish is gradually acquiring the characteristic shape of the adult, and 
the head is becoming twisted, the eye of the right side being dis¬ 
placed slightly downwards, and the eye of the left side coming into 
view over the top of the skull. (After Cunningham.) x 4. 
Fig. 7.—An adult Flounder showing the characteristic shape of 
the flat-fish, and the complete migration of the left eye over to the 
right side of the head. (After Buckland and Couch.) x | 
