462 J. FRANK DANIEL 
be attached by pads of tissue to the end of its own cerato- 
branchial and also to that of the ceratobranchial just in front. 
These hypobranchials then run posteriorly and medially to join 
unpaired cartilages soon to be described. 
The fifth branchial arch is greatly modified (fig. 14). Its 
pharyngobranchial segment has been so distorted as almost 
completely to change the appearance of the upper part of the 
arch. Its epi- and ceratobranchial segments (e.b.5 and c.b.6) 
are stout cartilages, devoid of branchial rays. The hypo- 
branchial segment is absent, and its ceratobranchial is attached 
directly to a median unpaired cartilage—the basibranchial (fig. 11). 
The median unpaired pieces and their relation to the segments 
of the arches are shown in figure 11. The most anterior of these is 
the basihyal cartilage, to which reference above has already been 
made and which may be described as a more or less star-shaped 
cartilage joining the right and left halves of the ceratohyoids 
in the mid-ventral line. It has an anterior triangular glossal 
projection (g.p.) which bends upward in the floor of the mouth 
to form a support for the so-called tongue. 
A first basibranchial cartilage has been mentioned by White 
(92, p. 299) as characteristic of Heterodontus (Cestracion). 
(See also Gegenbaur ’72, pl. 19, fig. 3). This, according to 
Gegenbaur, is located in H. philippi as a free nodule of cartilage 
in the middle line, posterior to the basihyal cartilage. For the 
same form Karl Fiirbringer, (’03) describes paired basal cartilages. 
In Heterodontus francisci I have not found either the azygos 
cartilage of Gegenbaur or the paired cartilages described by 
Fiirbringer. I have found, however, cartilages in this region. 
which I have described as extra-hyoid cartilages. These are 
identical in shape and direction with those given by Firbringer; 
but I am convinced that they are not first hypobranchial car- 
tilages since they lie superficial to the afferent artery. The sec- 
ond basibranchial forms a large median piece (b.b.) to which the 
hypobranchials of the second branchial arch are united. Pos- 
teriorly this median piece joins an enlarged backwardly-directed, 
arrow-shaped piece (m.p.) to which the third and fourth pairs of 
