182 EDWARD PHELPS ALLIS, JR. 
this cartilage being said to be fused with a cartilage ‘g’ in 
Chimaera, but a separate and independent cartilage in Callor- 
hynchus. Hubrecht considered both these cartilages of the 
Holocephali to be alar cartilages (‘Nasenfliigelknorpel’), and 
Schauinsland (’03) calls them nasal cartilages, but I consider 
the cartilage ‘f’ to be an upper labial cartilage. 
It is evident that the upper lip of Ceratodus, as defined Ne 
Ginther and confirmed by Greil, corresponds to the supra- 
maxillary fold of Chimaera. The upper lip as defined by Huxley 
was said by him to consist of two parts, one represented in a 
transverse integumental fold lying immediately anterior to the 
so-called vomerine teeth, and -the other by a fold extending 
forward from the angle of the gape of the mouth along the 
lateral edges of the nasal apertures. The former fold, as I find 
it, I consider to be a part of the primary upper lip of the fish, 
the other, which is hardly recognizable in my specimen and found 
only at the angle of the gape, being a secondary lip. The 
functional upper lip is then, as Huxley concluded, simply a fold 
of the dermis on the anterior part of the head, and is accordingly 
a tertiary upper lip lying anterior to the secondary one and 
circumscribing a second band of the external surface of the 
head which is here added to and included in the cavity of the 
mouth. 
These lips and the labial folds and furrows of Ceratodus are 
shown in the accompanying figure 12, and it is there seen that 
there are two angles to the gape of the mouth, one the actual angle 
and the other the apparent angle when the mouth is closed. 
The actual angle corresponds to the angle of the secondary lips 
of the Selachu, and immediately posterior to it there is a short _ 
flat flap of dermal tissues which is the hind end of the labial fold. 
This latter fold lies parallel to the dorsal surface of the mouth 
cavity, and its lateral edge lies slightly internal to the edge of 
the functional, or tertiary upper lip. Dorsal and posterior to 
this fold is the external opening of the so-called labial cavity 
of Ginther’s descriptions, that cavity lying dorsal to the cavity 
of the mouth and being the supramaxillary furrow of the present 
descriptions. In an earlier work (Allis, ’00) this furrow was 
