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The palatobasal depressions for the palatobasal processes of the 
upper jaw are well marked. 
The long cartilaginous eye- stalk is continuous at its proximal 
end with the cranial cartilage, and at its distal extremity, where it 
articulates with the sclerotic, it is cupped. 
A truncated rostrum projects from the fore part of the head. 
In a vertical longitudinal section of the skull in the mesial plane, 
the portion of the first vertebra which is continuous with the cranium 
is brought into view, and the notochord is seen as it passes from 
the vertebral column to the hinder wall of the pituitary fossa, where 
it terminates. Perhaps one of the most interesting features in this 
section is the presence of a canal, presumably the hypophysis canal, 
which runs through the cranial floor, generally upwards and back- 
wards to open near the foot of the pituitary fossa. 
The palatobasal processes of the upper jaw are well developed 
and each is surmounted by a nodule of cartilage. 
A median elliptical piece of cartilage lies between the anterior 
extremities of the mandibular rami. It seems that this cartilage has 
not been observed before in other Klasmobranchs. 
In connection with the hyoid arch there is in most cases a no- 
dule of cartilage at the free part of each cerato-basihyal articulation. 
There are occasionally two cartilages in this position, and in some 
cases they are absent on one or both sides. There cartilages do not 
appear to have been noticed before in any other shark. May they 
not represent hypohyal segments ? 
There is an interarticular cartilage in the ligament which passes 
from each hyomandibular cartilage to the lower jaw. 
The pharyngobranchial cartilages present grooves on their upper 
surfaces, on which the efferent branchial vessels rest, as they pursue 
their course from without inwards. 
Fossae for the attachment of the branchial adductor muscles are 
present on the epibranchials and ceratobranchials, with the exception 
of those belonging to the fifth branchial arch. 
The hypobranchials of the first gill arch are small. Those of the 
second arch are much larger and may either be distinct or may to- 
gether form a single transversely-placed plate of cartilage. 
The basibranchials or cartilages which occupy the mid- ventral 
position between the halves of the branchial arches, vary in number 
from five to eight. Attention need only at present be called to the 
first basibranchial, which, when present, is a nodule of cartilage situated 
between the basihyal and hypobranchial cartilages of the second arch. 
