Dr. Nugent on the Geology of the Island of Antigua . 46 S 
Cerithium, Ostrea, Trochus, Cyprea, Turritella, Verms, Lucina, &c. 
&c. Casts, principally siliceous, of Conus, Purpura, Voluta (Oliva) 
1 have likewise met with ; none of which appear to me to differ 
essentially from the varieties daily thrown ashore by the sea. In the 
marl, besides some of these genera, we have a singular association of 
three or four kinds of Helix,* (two or three of which appear in no 
wise different from the living species common every where in the 
island, Bulimus (Bulimulus of Leach), not known terrestrial or fluvi- 
atile here, with marine genera, as Murex, Area, Nerita, Purpura, 
Chama, Trochus (whelk), &c. resembling the recent species of the 
same shells. The most common of these shells, particularly in the 
yellowish marls, is the oblong and turbinated snail ; then the round 
and umbilicated shell the Bulimulus ; then the triangular bivalve 
Triquetra (Blainville) and other marine shells, f There is a most 
abundant fossil body in this marl also, which is vulgarly called 
ground-pearl : it is a very small fragile globular pearl-like substance, 
somewhat tubercular on the outside, and breaking into thin scales, 
with a circular opening on one side, looking like the cast ovum or 
larva of some insect, and generally filled with earth ; though brittle 
in the extreme when touched, the weather seems to have little or 
no effect on it; and it is found in prodigious quantity in the furrows 
of the land when newly turned up.J I know of no beds in which 
* One sent is of the genus Odontotrema of Dr. Leach. 
+ During a very cursory visit to Spanish Point, the south eastern part of the Island of 
Barbuda, distant about thirty-five miles to the northward of the marl formation of 
Antigua, and which is a particularly interesting spot, I found a yellow marl, containing, 
besides the same bulimus and helix, another species which I have not met with 
terrestrial, being less fragile and more rugose on the exterior, and having a notch-like 
indentation on the right lip ; and these were in close contact with shells decidedly marine, 
Pyrula, Trochus muricatus, Cyproea, and a large conch-like Buccinum; 
X A substance exactly similar to this is very frequently brought to England from the 
West Indies, with collections of recent shells* — Ed. 
Vol. V. 3 N 
