56 LIMA. 
although the animal is said to differ. In the young Magilus also, 
the inner lip is reflected over the body whorl, which is not the 
case in Leptoconchus, fig. 11. 
LEP’TON, Turton. Soren, Squamosus, Montf. Fig. 62. 
LIGAMENT. (From Ligo, bind.) The true ligament is always 
external, and serves the purpose of binding the two valves of a 
shell together externally by the posterior dorsal margins. There 
is another substance, called by Gray the Cartilage, which is elastic 
and of a condensed fibrous structure, placed within the Liga- 
ment, either close to it, or at a more interior part of the shell; itis 
sometimes contained in a pit formed for its reception, in the 
centre of the hinge. This substance being elastic, keeps the 
valves open, unless drawn together by the counteracting force 
of the adductor muscles. When conchologists speak of a shell 
as having the Ligament external, the real meaning is that these 
two substances are so close together, as in appearance to con- 
stitute one body. When two ligaments are spoken of, as in 
Amphidesma, the meaning is that the cartilage occupies a sepa- 
rate place on the hinge. 
LIGAMENTIFEROUS. (Ligament, and fero, bear.) Having or 
containing the ligament, as the cardinal pit in Mya, fig. 71. 
LI'GULA. Montagu. A genus containing the more rounded and 
less gaping species of Lurraria, Auct. Fig. 77, Lutraria 
Papyracea. 
LI'GUUS. Montf. A genus containing species of Acnatina, Auct. 
which have rounded apertures and lengthened spires, differing 
from his PotypHemi, which have lengthened apertures. A. vir- 
ginea, Auct. fig. 286, is the type of this genus. 
LIMACINEA. Lam. A family of the second section of Lamarck’s 
order Gasteropoda, containing the genera Parmacella, Limax, 
Testacella and Vitrina. ‘Tothese may be added Plectrophorus 
and Cryptella. 
LIMA. Brug. (Lima,a file.) Fam. Pectinipes, Lam. Subostra- 
cea. Bl. Descr. Equivalve, inequilateral, compressed, oblique, 
auriculated, oval, radiately ribbed, or striated, imbricated, covered 
with a light brown epidermis; hinge with a triangular disc 
between the umbones, divided in the centre by a triangular 
ligamentary pit, without teeth; muscular impression, one, sub- 
lateral, sub-orbicular. Obs. The shells thus described are marine, 
two or three species being found on our coasts, and fossil species 
occuring in Lias, inferior Oolite, Calcaire-grossiér, &c. They 
differ from Pecten, in having a wide hiatus for the passage ofa 
byssus, by which they are occasionally attached, and also in the 
triangular disc, which separates the umbones. The animal 
makes use of the valves of his shell as natatory organs, working 
them like fins or paddles, and by this means proceeding at a rapid 
rate through the waters. L. Squamosa, fig. 174. 
