138 Mr. H. G. Seeley on Prof. Owen's 
Ornithosaurian cranium. It a Vor to me to demonstrate 
that there can be no doubt about Von wai af RR Mi 
stru 
the grounds on which Von Meyer pronounced definite judg- 
ment in the matter. If Prof. we was conversant with the 
facts, as I have here figured them, this is a gross misrepre- 
sentation of Von Meyer; and if he was not cognizant of the 
true structure of the bird's skull, the remarks upon Von Meyer 
which I have quoted should not have been written. German 
Ornithosaurians differ from birds in having a postfrontal bone 
of Lacertian form ; but the fact that that bone may articulate 
with the squamosal does not alter the avian characters of the 
squamosal bone, which does not enter, in any reptile, into the 
formation of the cranial cavity. 
Prof. Owen states that the quadrate bone (tympanic, Owen) 
is immovably articulated to the squamosal (mastoid, Owen), 
opisthotic (paroccipital, Owen), and quadrato-jugal (squamosal, 
Owen). These relations are not evident either from the de- 
the nasal and orbital holes; and in this character they are 
matched by most Pterodactyles. Prof. Owen reminds us that 
a representative of this foramen characterizes the extinct Te- 
se sores ruminant mammals any reasoning on affinity 
from isolated characters is calicis absurd; and this charac- 
ter, as reptilian, avian, or mammalian, can ‘only have weight 
in the sum of those characters which define the animal’s 
plan of structure. 
