DESCRIPTION OF REPTILES. 215 
Four vertebrae of progressively increasing size repeat the characters of the 
vertebra fig. 7: i.e. they have the fore-part of the under surface between the 
diapophyses excavated, and have only one hypapophysis, viz. that developed 
from the hind-part of the under surface; they have also the epizygapophyses 
nearly vertical, and raised high above the prezygapophyses. A vertebra of 
the same size as the largest of these four repeats the general characters of the 
small vertebra fig. 8: it has the anterior hypapophysis as well as the posterior 
one; larger terminal cup-and-ball surfaces in proportion to its size; smaller 
intervals between the epi- and pre-zygapophyses ; less lofty posterior aliform 
productions of the neural arch, and the base of the neural spine extending nearly 
to the fore-part of that arch. 
Both the above-contrasted vertebrae from Bracklesham agree in general size with 
those of a chain of six vertebra from Sheppey, of which two are figured at fig. 14, 
but are shorter in proportion to the size of the articular ends: the length of the 
neural arch, at and including the inferior zygapophyses, is 2 centimeters in the 
Sheppey vertebre and | centimeter 7 millemeters in the Bracklesham vertebre, 
the articular cups and balls being of equal size in both vertebre : the Sheppey 
vertebre differ from both kinds of Bracklesham vertebre in the continuous ridge 
or keel along the under part of the body (fig. 15): the neural arch is less sud- 
denly compressed above, or inclines more gradually to the base of the spine. 
Of the ten larger vertebrae from Bracklesham with both anterior and posterior 
hypapophyses, two (figs. 9 & 10) differ from the rest in having a strong external 
Paleophis porcatus. Paleophis porcatus. 
ridge extending from the anterior (ze) to the posterior (z e') lower and external 
zygapophyses on each side of the neural arch. On comparing one of these ver- 
tebra with another of the ordinary character and of the same size, the following 
further differences presented themselves: in the ridged vertebra, which may be 
2F2 
