CHONDROCRANIUM OF EUMECES 165 
of the columella. If the columella is of hyoid origin and has 
reached the capsule from the outside, clearly the perichondrium 
of the outside of the otic capsule must be pushed in before the 
footplate of the columella; on the other hand, if the columella 
be of otic origin and its footplate has developed in situ, the 
outer perichondrium of the capsule must also pass continuously 
over the outer surface of the footplate. This would seem a 
safe criterion, but it has led Versluys and Fuchs to diametrically 
opposite conclusions. In the periosteum of adult lizards Ver- 
sluys finds the first condition general; in the perichondrium of 
embryos of Lacerta and the geckos and in the periosteum of 
adult Lacerta vivipara and Phyllodactylus, Fuchs describes the 
second condition, although recognizing the correctness of Ver- 
sluys’s observations for other adult forms. In this confusion, 
it seems clear that embryonic conditions are more likely to give 
a correct clue than are adult conditions—that the adult perios- 
teum is more liable to secondary modification than the embryonic 
perichondrium. In embryos of Eumeces I have found the exami- 
nation of this point surprisingly difficult. In earlier stages the 
perichondrium is very indefinite or unrecognizable; cartilage and 
perichondrium are developing out of a common undifferentiated 
embryonic matrix. In spite of difficulties, however, the evidence 
seems to me conclusive that there is no pushing in of an outer 
perichondrium before the columella, but that the outer covering 
passes without interruption, as described by Fuchs, over the wall 
of the otic capsule, the membrana ovalis, and the footplate of 
the columella. 
In Eumeces the evidence points consistently to the genetic 
relationship of otic capsule and otostapes. The confusion of 
data for other reptiles seems, on the whole, to favor the same 
view; such cases of striking independence as Platydactylus and 
Gecko, rather than the far more numerous cases of close em- 
bryonic connection, would appear to be the exceptions demanding 
special explanation. This interpretation gains additional force 
from the presumption of at least a partial homology of the 
reptilian columella and the physiologically corresponding struc- 
tures of the Amphibia, together with the general recognition of 
