343 
10) Auditory region. Suprapharyngobranchial I is very large 
in Polypterus. It is grooved for the passage of the first branchial 
vein. From its base the infrapharyngobranchial extends forwards and is 
attached to the inferior side of the wing of the parasphenoid. The 
ceratobranchial is supported by a very stout suspensory ligament from 
the parasphenoid. There appeared to be no separate epibranchial. 
The suprapharyngobranchial ar- 
ticulates with the auditory capsule paper et ines prom 
and the commencing bone shows ee : . 
the signs of a tendency to become Er 
separateand hereinisseen the 
origin of the “stapes” or 
“operculum” of the Uro- 
delan ear. The Urodela no 
longer possess pharyngobranchials. 
The operculum may even develop 
as a separate nucleus of cartilage 
and the connection with the qua- 
drate as in Menopoma is secondary. As in the Dipnoi the hyoman- 
dibular in Urodeles has disappeared and the hyoid arch is suspended 
by ligaments which may enclose a stylohyal. 
11) Ceratodus and the Holocephali. If the Urodela are 
to be derived from the Crossopterygidae the Dipnoi and Holocephali 
must occupy a different portion from that usually accorded them. One 
of the crucial points is the relation of the quadrate to the skull. In 
the Dipnoi and Holocephali the quadrate and whole palatine arch 
are fused with the skull cartilage. Presuming the Dipnoi to be in the 
ancestral line of the Urodela such should be the condition in young 
and primitive Urodeles. Such is not the case. In a young Meno- 
poma the relations ofthe quadratearevery nearly those 
of Polypterus. Only the anterointernal process of the quadrate 
is fused with the cranial cartilage. In Urodeles generally the ptery- 
goid cartilage lies at a considerable distance from the base of the 
skull. 
That the Holocephali are related to the Dipnoi has been abund- 
antly shown but the nature of the relationship has been misunder- 
stood. To take one point — the mucous canals correspond in dis- 
position to those in the Dipnoi and are actually surrounded in 
part by small bones which are the last remains of the completer 
armature of the Dipnoi or their ancestors. The “labials” of Dipnoi 
correspond to the small semidetached projections of the nasal carti- 
