90 Proceedings of the Loyal Physical Society. 
points projeeting forward from the anterior margin of the skull 
(Woodcut, ¢.): The posterior division of the skull (Woodcut, 
p.a.) is flatter than the anterior, but 
the median furrow or groove is still 
observable, though not so sharply 
defined. r 
The most natural interpretation of 
these appearances seems to be this, 
—that we have here a primitive 
cranium composed of calcified carti- 
lage, as there are no_ reliable 
evidences of discrete ossifications, 
—that the posterior part represents 
the parachordal elements fused with 
the ear capsules, while the anterior 
part consists of the trabeculae, fused 
with an element on each side repre- 
senting the palatine cartilage of the 
lamprey —and that the anterior 
border of the head, with its four 
points or cirrhi, represents the upper 
margin of a suctorial mouth. There 
seems to be no basicranial fontanelle. 
I have already said that in almost 
every case the surface of the head 
is more or less eroded and broken 
through, and the effects of this 
wearing are seen in Figs. 1, 4, 
and 5. Naturally the more pro- 
minent parts on each side of the 
median groove are the first to go, 
Putbssbpondniicsfunnk Tred, and consequently the circumference 
Magnified restored outline, Of the anterior part of the skull is 
the head seen from the ventral apt to remain in a ring-like form, 
PET TREN Hz onnterion while the rest is more or less worn 
artotheahtiifns il aisaatute: away. That this is the origin of 
likestructure behind the head. the appearance interpreted by Mr 
Smith Woodward ‘as an oral ring, and compared by him to 
the annular cartilage of the lamprey, there can be no manner 
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