54.4 FRANCIS VILLY. 
when contact takes place the relation is only one of close 
juxtaposition. 
From the above account it is clear that the constituent cells 
of the annular cartilage appear in connection with the anterior 
part of the mandibular arch, and are perhaps derived from it ; 
although it is possible that they may be merely concentrated 
from the scattered cells surrounding the distal end of the 
Eustachian tube. The point at which the cartilage originates 
is in front of and below the eye, and the part of the mandibular 
arch to which it is applied is the palatopterygoid bar. 
The remaining two skeletal elements are closely connected 
in the adult, though not actually fused. The stapes forms a 
concavo-convex cartilage, stopping the fenestra ovalis; whilst 
the columella is a rod inserted in front of the stapes, between 
it and the auditory capsule, and expanded distally against the 
tympanic membrane (see figs. 17 and 18). Professor Parker 
calls the proximal end of the columella interstapedial and the 
remainder the mesostapedial. 
The stapes may be dismissed with very few words. It is 
formed as a chondrification in the capsular membrane closing 
the fenestra ovalis, at a period when the remainder of the cap- 
sule is well developed, and not long before the tadpole begins 
to assume the frog’s form. No more need be said of it here, as 
Professor Parker has described this cartilage in his account of 
the frog’s skull. 
The third and last of the skeletal elements mentioned has 
now to be considered. As faras I can make out, the columella 
is embryologically to be considered, not as a part of either the 
hyoid or mandibular arches, but as similar to the stapes in that 
it originates in the membrane closing the fenestra ovalis. In 
this my results agree with those published in Professor Cope’s! 
recent paper, as they also do concerning the separate origin of 
the columella and annular cartilage. 
I have found the columella in the same specimen which 
showed the origin of the annular cartilage. Just in front of 
1 “Hyoid and Otic Elements of the Skeleton in the Batrachia,”’ ‘ Journal 
of Morphology,’ vol. ii, No. 2, November, 1888. 
