124 
I CRT 11YOSA URIA 
Case. Shelf. Specimen. 
88 a unusually short from front to back, and 
should be contrasted with the corresponding 
vertebrae from the Cambridge Greensand. 
a 5 longitudinal section through 6 associated verte¬ 
brae of Ichthyosaurus [apparently mid-dor¬ 
sal], showing the lozenge-shaped section of 
the intervertebral space. It also shows the 
section of the centrum like two cones op¬ 
posed and meeting at their apices. The 
osseous structure is well seen. 
a G a small caudal vertebra, with sub-circular 
intervertebral articular side two inches in 
diameter. 
a 7 14 lower dorsal vertebrae (associated) of a 
small Ichthyosaurus from Whitby. In the 
last the two tubercles are blended into one 
oblique tubercle; this vertebra is usually 
considered pelvic or sacral. Both the ribs 
and neural arches are preserved. The latter 
exhibit the flattened neural spines adjacent 
superiorly, and the front and back zygapo- 
physes looking obliquely upward and down¬ 
ward. 
88 b 1 tooth of Ichthyosaurus platyodon. It is flat¬ 
tened from side to side so as to form sharp 
lateral ridges as in Dakosaurus, and as in 
that genus the crown of the tooth curves 
inward. There is a resemblance in the 
crown being nearly smooth. The fang is 
very long, massive, and quadrate ; on each 
side it is vertically ridged, the ridges being 
continuations of those folds of the dentine 
which are seen in sections of the crown, 
and covered with enamel. The folds become 
rugose at the base, where the pulp-cavity 
is closed. The hemispherical excavation at 
