— = 
from the Lias and Oolites. 29 
uniform size around the base; but it is readily distinguished 
from D. depressum by the number and greater development of the 
tubercles of the ambulacra, which maintain their size throughout ; 
whilst in D. Moorei the ambulacral tubercles are fewer in num- 
ber and rudimentary in size in all the upper part of the areas. 
The contour of the test moreover does not assume the penta- 
gonal outline of D. depressum, nor has the upper surface of the 
interambulacral areas the median depression seen on the test of 
the latter. The mouth-opening is larger, and the decagonal 
lobes are more equal in size in D. Mooret than in D. depressum. 
Locality and stratigraphical range-—We have collected D. 
Moorei in the Upper Lias of Gloucestershire. Mr. Moore found 
it in the same stratum near Ilminster with Ammonites communis 
and A. serpentinus. Professor Deslongchamps has communicated 
a specimen of this Urchin which he found in the Lias supérieure 
of May, Calvados, associated with Leptena Davidsoni and The- 
cidea Bouchardii and several other species. 
We dedicate this species to Mr. Moore, of Ilminster, whose 
assiduous researches have brought to light so many interesting 
forms from the Upper Liassic beds of Somersetshire. 
Genus Pepina, Agassiz. 
As this genus was incorrectly defined in our memoir on the 
Cidaridee, it having been there stated that the mammillary emi- 
nences were “ crenulated like those of Diadema,” we take this 
opportunity of correcting the error, and giving a definition more 
in accordance with our present knowledge. 
Test thin, circular, more or less depressed ; primary tubercles 
small and perforated ; mammillary eminences with smooth ring- 
like summits without crenulations ; pores in general disposed in 
triple oblique pairs; mouth small and slightly decagonal, mar- 
gin not much notched; ovarial disc small and not prominent ; 
ambulacral areas with one, two, or more rows of small tuber- 
cles ; interambulacral areas sometimes with two rows only, some- 
times with two rows and additional secondary rows of tubercles 
more or less complete. 
This genus is extinct, and is found in the oolitic cretaceous 
rocks. 
Pedina Bakeri, Wright. PI. 1. fig. 4, a-c. 
Test circular, depressed ; ambulacral areas narrow, with one row 
of small tubercles disposed in a slightly zigzag line down the 
centre of the areas ; interambulacral areas broad, with two rows 
of primary tubercles raised on prominent mammillary emi- 
