126 
ICHTHYOSA URIA 
Case. Shelf. 
88 c 
c 
c 
c 
c 
Specimen. 
attachment to the flattened hone (pm 22), 
the premaxillary, which on its inner side is 
supported by a similar thin bone (n 15) on 
each side, which arch over above and meet 
in the mesial line ; these bones are the nasals; 
they form three sides of the quadrate empty 
space in the skull, of which the base is 
made by the palatal bones. 
The four bones on each side below are a section 
of the lower jaws. 
the ends of this section of jaws are polished. 
c 1 
The proximal end is cut off from —. 
oo 
In 
the smaller end the pre-sphaenoid is seen 
to have disappeared; the vomera being ad¬ 
jacent and sub-ovate. The pre-maxillaries 
attain a greater developement and appear 
to take the place of the maxillaries. The 
teeth may be seen in the alveolar groove. 
In the lower jaw three bones on each side 
form the mandible. 
3 section of jaws, chiefly valuable as showing 
sections of teeth in situ. 
4 more distal part of the jaws c 1 and c 2, 
polished at the anterior end, in which the 
vomera and nasal bones are not prolonged, 
and the jaw is formed by the premaxillary 
bones. 
5 anterior terminal part of the same jaws. 
88 c 1 cranial region of skull of Ichthyosaurus from 
Barrow-upon-Soar, displaying on the palatal 
surface the basi-sphaenoid and connate pre- 
sphaenoid style. On the right is seen the 
pterygoid narrowing and emarginate exter¬ 
nally as it passes behind the basi-sphaenoid, 
after which it again appears to expand and 
become the outer inferior wall of the tern- 
