36 Dr. T. Wright on new Species of Echinodermata 
tubercles on each side of the margins of the area, between these 
are several rows of small granulations arranged without much 
order; at the base of the area ten larger tubercles are disposed 
in pairs, the tubercles on the right side alternating with those 
on the left; the interambulacral areas are about twice the width 
of the ambulacral ; a single row of tubercles occupies the centre 
of each of the two columns of plates, and numerous smaller 
tubercles degenerating into mere granules cluster around the 
base of the large tubercles; a second row of tubercles extends 
upwards from the basal angle towards the equator, where it ter- 
minates ; the basal tubercles consisting of about six pair occupy 
all the base of the area—they are about the same size as those 
of the ambulacra, but are arranged somewhat less regularly. 
The median depression in the centre of the interambulacra is 
very well marked in this species, so that the test has the appear- 
ance of being divided into fifteen lobes. The anal plates form a 
promment narrow ring around the oblong anal opening, and the 
eye-plates are closely soldered to them ; the eye-holes are very 
distinct mm most of our specimens. The mouth-openmg is of 
moderate size, and is slightly decagonal; the poriferous avenues 
lie in considerable depressions of the test, which throws the am- 
bulacral areas into prominent relief from the interambulacra. 
Affinities and differences—The marginal rows of tubercles on 
the ambulacra, and the central rows of tubercles on the plate 
columns of the mterambulacral areas serve to distinguish this 
species from P.nodulosus. It has a considerable resemblance to 
the young forms of Kchinus germinans, but the regularity of the 
rows of tubercles on the sides and upper surface of the test, 
and the size and arrangement of those at the base afford good 
diagnostic characters by which it may be easily distinguished 
from that common form ; the same group of characters serves to 
distinguish it from Arbacia Forbesii. 
Locality and stratigraphical range.—We have only found this 
species in the Pea-grit of Crickley Hill; all the other specimens 
that were collected by Mr. Gibbs of the Geological Survey, were 
found in the same bed of this locality. 
We dedicate this fossil to Professor Deslongchamps of Caen, to 
whom palzontology is indebted for many important contribu- 
tions to the Oolitic fauna published in the ‘ Mémoires de la 
Société Linnéenne de Normandie.’ 
Nucleolites Woodwardu, Wright, 1852. PI. IL. fig. 5, a-e. 
Test subquadrate, sides tumid, dorsal surface flatly convex, anal 
valley deep, narrow and spear-shaped, extending from the 
apical dise to the posterior border ; ambulacral areas narrowly 
