300 COPE. [ Von. ite 
In Dermophis (mexicanus) the stapes is lateral in position, 
and is osseous. Its columella is robust and osseous, and extends 
forwards, abutting against the posterior border of the quadrate, 
with which it forms a close movable articulation. The quadrate 
is completely osseous, and is freely articulated proximally with 
the cranium. The ceratohyal is free, and not connected with 
the suspensorium. 
Pseudosauria. 
De Blainville ; IZyctodera, J. Miiller. 
This extensive group is most conveniently considered by 
families. 
In the Amblystomide the columella of the stapes is replaced 
by the stapedius muscle. This is directed posteriorly, and away 
from the suspensorium. The ceratohyal is short distally, and 
its extremity is articulated to the distal part of the posterior 
border of the quadrate cartilage. The quadrate cartilage is 
ossified distally, but not proximally. 
In the Plethodontidz the stapes has the same character as in 
the Amblystomidz, except that in some specimens a slender car- 
tilaginous process is seen to be directed towards the quadrate car- 
tilage in Plethodon glutinosus and Spelerpes ruber. This is 
probably the persistence of the larval condition of both this fam- 
ily and of the Amblystomidz. In the larva (Pl. I, Figs. 7, 9) 
the columella of the stapes is directed forwards, and is con- 
nected with the proximal part of the quadrate cartilage by a 
short cartilaginous rod. In the larva of Chondrotus tenebrosus 
the connection is completed for a short distance by ligament. 
Thus the larvee of these two families present the character of 
the mature members of the suborders Trematodera, Amphiu- 
moidea, and Pseudophidia. The quadrate in the Plethodontidze 
is ossified in its proximal part only. The ceratohyal has its 
distal extremity curved forwards, and articulated by distinct 
suture with the quadrate cartilage or bone; in Plethodon glutt- 
nosus it is inserted in a fossa (Pl. I., Fig. 14). 
In Desmognathidz the characters are as in Plethodontidez. 
In Salamandridz the position of the stapes is as in the 
previous families, but the relations of the extremity of the 
ceratohyal are as in the larve of those animals, or as in the 
