CARDIUM proboscideum. 
TAB. CLVL— Fig. 1. 
Spec. Char. Suborbicular, gibbous; anterior side 
straight, about 20 longitudinal rows of large 
canaliculated spines, with two rows of lesser 
ones between each cover the surface. 
1 his corresponds in form with Cardium ciliatum, but 
the disposition of the rows of spines is altogether dif- 
ferent and the shell is thicker : a few of the last formed 
thorns on the posterior side are very large and clumsy, 
and serve to relieve the elegant proportion of the others. 
This elegant shell very rarely remains so finely re- 
placed and in so extraordinary a manner as this specimen 
in semitransparent calcedony, covered by Cachalong, 
becoming transparent when wet and more opaque when 
dry. I am favoured with it by Miss Hill, from Black- 
down, near Cullumpton, Devonshire. The larger 
doubled aculei are elegantly cast and with extreme 
neatness, as well as the two smaller rows, making 
generally three sets of aculei, and distinguishing it 
from any recent species : a few of the aculei are 
widened in an extraordinary manner, but they appear 
as if they were so in the original or recent state of 
the shell. It may be expected that the Lime of the shell 
has been carried away with the acting fluid that held the 
Calcedonie matter in solution to fill the space by some 
chemical means, with which we are as yet unacquainted. 
What information we may gain on this point by means of 
pur new apparatus, we know not. The sand in which 
