from the Lias and Oolites. 21 
clay near the Tetbury Road Station, Great Western Railway, 
closely resemble this form ; but as no entire specimen, that we are 
aware of, has been found, it is impossible to state whether it has 
a wider range in the higher beds of the lower division of the 
Oolites or not. 
We dedicate this species to our friend M. Bouchard Chantereaux 
of Boulogne, to whom we are indebted for some beautiful and 
rare specimens of Echinoderms and other fossils from the rocks 
of the Boulonnais, most kindly contributed by him to aid us in 
the composition of these memoirs. 
Hemicidaris minor, Agassiz. PI. I. fig. 3, a-c. 
Syn. Hemicidaris minor, Agassiz, Catalogus Systematicus, p. 9; 
Agassiz and Desor’s Catalogue raisonné des Echinides, Annales 
des Sci. Nat. tom. vi. p. 339. 
Acrosalenia rarispina, M‘Coy, Aun. of Nat. Hist. 2nd Series, vol. ii. 
p- 411. 
Test hemispherical above, flat at the base; ambulacral areas 
slightly flexuous, not prominent, with six large tubercles at 
their base, and four rows of small unequal-sized granules in 
the middle, diminishing to two rows in the upper part of the 
areas ; interambulacral areas three times the width of the am- 
bulacral, with three primary tubercles on the upper surface 
and three smaller ones at the base ; the wide intertubercular 
spaces are covered with small distinct nearly equal-sized gra- 
nules, which form complete circles around the margins of the 
areolas of the primary tubercles ; the apical disc is of mode- 
rate size, and its ovarial plates are covered with a delicate gra- 
nulation; base flat, mouth-opening large and decagonal ; 
pores arranged in the avenues in a single file throughout. 
Height ,6,ths of an inch, transverse diameter Zyths of an inch. 
Description.—This beautiful little Urchin was first discovered 
in the étage Bathonien of Langrune, Calvados, the true equiva- 
lent of the Great Oolite of English geologists; it was entered 
in M. Agassiz’s ‘ Catalogus Systematicus*’ as Hemicidaris minor, 
from specimens sent to him by M. Michelin ; it afterwards found 
a place in the ‘ Catalogue raisonné des Echinides’ of Agassiz and 
Desor, accompanied with this remark : “ Se distingue entre tous 
les Hemicidaris par les tubercules trés espacés, dont il n’y a que 
deux ou trois dans une rangée.—Terrain Jurassique de France.— 
Michelin.” Professor M‘Coy, in his paper “On some new Me- 
sozoic Radiata+,” afterwards described this Urchin under the 
* Catalogus Systematicus Ectyporum Echinoderm. Foss. Mus. Neoco- 
mensis, 1840. : . °: 
+ Annals of Natural History, Qnd Series, vol. ii. p. 411. 
