38 GUIDE TO THE FOSSIL REPTILES, AMPHIBIANS, FISHES. 
Wall-cases 
15-17. 
Stands 
A-C. 
Table-cases 
20-23. 
Case H. 
also supplemented by other small bones (Fig. 38). These 
reptiles (Fig. 34) are well illustrated by a unique collection 
Fig. 35.—Skull and mandible of Ichthyosaurus zetlandicus, from the Upper 
Lias of Normandy; about one-quarter nat. size. A. orbit; ang. angu¬ 
lar ; d. dentary ; Fr. frontal; J. jugal; h. articular ; Md. mandible ; 
Mx. maxilla; N. nares ; Na. nasal; op. splenial; Pa. parietal; Pmx. 
premaxilla; Por. postorbital; Prf. prefrontal; Ptf. postfrontal; QuJ. 
quadratojugal; S. supratemporal fossa; Scl. sclerotic ring; Sg. 
squamosal; St. supratemporal. (After Zittel. Table-case H.) 
of skeletons, chiefly from the English Lias, in Wall-cases 15, 
16, 17, and by smaller fragments in Table-cases 20 to 23. 
The large head (Fig. 35) is shaped like that of a porpoise, 
with an elongated snout and with 
powerful conical teeth (Fig. 36) set 
in a groove along the edge of the 
jaw. The nostril is just in front 
of the enormous eye, and this is 
strengthened by a ring of sclerotic 
plates which would help in focussing 
for varying distances. There is a 
conspicuous pineal foramen for a 
median eye in the top of the head 
(see skull in Table-case 21). The 
vertebrae (Fig. 37), which are very 
numerous, short, and biconcave, are 
shaped like those of a fish to insure 
flexibility of the backbone. The 
Fig. 36.—Tooth of Ichthyo- neck is quite short, while the ver- 
saurus campylodon, from tebrae of the tail are sharply turned 
the Lower Chalk of q own a t some distance from the 
Folkestone ; nat. size. , J . , . . 
(Table-case 20 ) end, to support a triangular vertical 
