56 
overlooked, from its smallness. It is nevertheless very dis- 
tinct and pretty when examined. I have only seen single 
valves, they are accompanied by some Anomiae, &c. 
LINGULA ovalis. 
TAB. XIX.— Fig. 4, 
Spec. Char. Depressed, oblong-oval, anterior edge 
circular, beak very short. 
Half an inch long, a quarter of an inch wide. The 
young shells of L, mytilloides, although they scarcely 
show the truncated edge, are to be distinguished by their 
being more elevated in the middle, and more acute at the 
posterior edge. 
1 have only seen a cast of this species, it was found in a 
lump of a hard white marley stone, among the sand, above 
the Clay stratum near Pakefield in Suffolk, by Mr. John 
Thurtell, who has favoured me with some curious shells 
from that county, it is accompanied by some striated 
Ammonites, Tellinae, &c. 
This genus of shells does not appear to have been noticed 
as fossil. It is very rare in the recent state, and I believe 
but one species is known, which Linnaeus, having seen only 
one valve, very naturally called Patellaunguis.* The speci- 
men from which Cuvier’s figure in the Annales du Museum 
is taken, is one of those which were originally Seba’s. 
Cuvier dissected it, and has given figures of all the parts of 
the animal, from which it appears that the shell is covered 
with a membrane, by the action of which alone it is enabled 
to open its valves. The animal has two tentacula or arms, 
with which it procures its food and conveys it to its mouth , 
He found that it has two hearts. 
* Mr. Sowerby has published a plate containing figures of the recent species 
of this genus from good specimens in Mrs. Mawe’s collection ; it may be had 
separate. 
