28 ‘Dr. T. Wright on new Species of Echinodermata 
After a diligent search for Urchins in the Lias of Glouces- 
tershire, we have succeeded in collecting only a very few examples 
of this group from these rocks. In addition to those found here, 
our friend Mr. Moore of Ilminster kindly presented us with a few 
specimens which he collected from the Upper Lias near Ilminster, 
and from these collective materials the species under consider- 
ation was discovered. Diadema Moorei has a circular outline 
slightly inclining to a pentagonal contour ; it is much depressed 
at the upper surface and is flattened at the base. The ambu- 
lacral areas are very narrow, being less than one-third the width 
of the interambulacral ; their margins are occupied by two rows 
of tubercles about eight in each row, which, at the base and up to 
the equator, are nearly as large as those of the interambulacra ; 
but from that region to the apex of the area they rapidly dimi- 
nish in size, and are here very disproportionate in magnitude to 
them ; a zigzag line of single granulation separates the two rows 
of tubercles from each other. The interambulacral areas are 
wide and well developed, and have two rows of tubercles, from 
8-9 in each row, which occupy the centre of the plates; the 
areolas of the tubercles on the upper surface are surrounded with 
a circle of granules which separates them from each other, but 
those of the base are confluent above and below. The inter- 
tubercular surface at the base of the test has a number of gra- 
nules scattered over it, whilst on the upper surface, the plates are 
destitute of any other ornament beyond the faint circles that 
surround the tubercles. The pedal pores are arranged in pairs 
in a single file; the avenues are, however, rather flexuous be- 
low; the basal tubercles of both areas are nearly alike in size, 
but on the dorsal surface those of the ambulacra dwindle into 
large granules, whilst those of the interambulacra maintain their 
size up to the last pair, which are small near the margin of the 
disc. The mouth-opening is large, and its margin is divided 
into ten nearly equal-sized lobes. The apical disc is partly pre- 
served in the specimen here figured ; it consists of five large ovarial 
plates of a heptagonal form ; two of the sides unite with the in- 
terambulacral plates, two with the ocular, two with the adjoin- 
ing ovarials, and the single surface contributes to form the 
boundary of the anal opening, which is of moderate size; the 
five ocular plates are small and heart-shaped, their apex is di- 
rected towards the anal opening, and their base to the area ; the 
madreporiform tubercle is slightly elevated on the single ovarial 
plate, and the surface of the discal plates is almost destitute of 
sculpture or granulation. 
Affinities and differences.— D. Moorei resembles D. depressum, 
Ag., in the depression of its upper surface and the flatness of its 
base, likewise in having the tubercles of both areas of nearly a 
