398 HOWARD AYERS 
jaw bar is separated from the mandible or basal part and has 
the same attachment, viz., to the hyoid, not at the tip, but fur- 
ther back, as shown at b, figure 10. This distal part is composed 
of seven pieces of cartilage on each side of the head; the basal 
piece is strongly attached by tendon to the dorsal edge of the 
hyoid and bends upward and forward to connect midway to the 
nose with the second segment, 4, the body of which is sickle- 
shaped, curving forward and inward to its attachment to 5, 
at the side and in front of the nasal capsule. Segments 3 and 4 
span the distance between the ventral mandibular territory to 
the nasal region and the maxillary territory. Segment 4 has 
a prong which leaves the curve of the sickle about midway and 
runs up, back and inwards, to attach at the side of the skull. Seg- 
ments 6, 7, 8, and 9 are, respectively, the equivalents of the 
first, second, third, and fourth tentacles of Bdellostoma. The 
cornual and subnasal cartilages do not seem to be represented 
as separate cartilages in Callorhynchus unless the cartilage of 
the median nasal fold is the remains of the subnasal bar of Bdell- 
ostoma. The long nasal tube of the latter is reduced to the 
capsular parts, which in Callorhynchus are well developed as two 
deep cartilaginous pockets set on either side of the median nasal 
cartilage. Callorhynchus has in addition a large long median 
dorsal snout cartilage which extends forward into the fleshy snout. 
The two cartilages of the first and second tentacles extend into 
the snout along either side of and somewhat ventrad of the 
median snout cartilage. 
The large hyoidean support cartilage lying below the mandible 
in Callorhynchus was called by J. Miller a second lower jaw, 
and he held it to be a peculiar cartilage not belonging in the 
vertebrate plan of structure, in which category he also placed 
the lower labials of Callorhynchus and other cartilaginous fishes. 
G. B. Howes homologized the labials of Callorhynchus with 
the mouth supports of Bdellostoma, but failed to see the relations 
of these parts to the mandibular cartilages and did not under- 
stand the morphological nature of this apparatus. His homol- 
ogies are correct only in part. 
The relation of the parts in Chimaera is shown in figure 30. 
They are reduced in number in this species and as a whole fall 
