ae LUCINA. 59 
ye 3 
- LITUA’CEA. Bl. The second family of Polythalamacea, Bl. 
partly corresponding with the “ Lituolées,’’ Lam. and containing 
the genera Lituola, Icthyosarcolites, Spirula, Hamites and 
Ammonoceras. 
LITUI'TUS. Montf. Srrrotma, Lam. Microscopic. 
LI'TUOLA. Lam. A genus of microscopic Foraminifera. 
LI'TUOLA. Lam. The third family of Polythalamous Cephalo- 
poda, Lam. containing the genera of microscopic Foraminifera, 
Litucla and Spirolina. The genus Spirula, also placed in this 
family, does not by any means agree with Lamarck’s definition, 
“« the last whorl terminating in a straight line.” 
LOBA’RIA. Schum. Sanevurnovaria rosea, Lam. Fig. 98, and 
other similar species. 
LOBA’TULA. Fleming. A genus composed of two very minute 
species of chambered shells. Serpula lobata, and S. concame- 
rata, Mont. Test. Brit. 515. 
LOMAS'TOMA. Rafinesque. An imperfectly defined genus, pro- 
bably belonging the Limnacea. 
LONGITUDINAL. Lengthwise. Longitudinal striz, ribs, &c. 
are those which radiate from the apex, and follow the spiral di- 
rection of the whorls in spiral shells; and from the umbo to the 
ventral margin in univalves. The term “ decourantes,’’ is em- 
ployed by French conchologists. The bands in Achatina, fig. 
286, are longitudinal or spiral. 
LORIPEDES. Poli. A genus composed of species of Lucina, 
Auct. in which the lunules are not prominent. 
LOTORIUM. Montf. <A genus composed of species of Trrron, 
_ Auct. in which the aperture is effuse. T. Lotorium, fig. 400. 
LOT’TIA. Gray. ParetiorpEes. Quoy and Gaimard. Fam. 
Phyllidia, Lam. Descr. Patelliform, rather flat, apex obtuse, 
leaning towards the posterior margin; muscular impression not 
symmetrical, but widest on the right side near the head of the 
animal; central disc of a variable brown colour. Obs. The 
shells of this genus so closely resemble Patella, that it is almost 
impossible to make the distinction from the shells alone. They 
are, however, generally flatter, and have the apex placed some- 
what nearer the posterior margin. The animals are very dis- 
tinct. Fig. 231, L. Antillarum. 
LUCER’NA. Humph. A generic name applied to some species. 
of Hexix included in De Ferussac’s sub-genus Helicogena. 
LUCINA. Brug. Fam. Nymphacea, Lam; Conchacea, Bl. 
Descr. Equivalve, inequilateral, orbicular, lenticular, radiately: 
striated; hinge with generally two minute, cardinal teeth, 
which are sometimes nearly obsolete, and two lateral teeth on 
each side of the umbo in one valve, one in the other; ligament 
external, partly hidden by the margins of the valves when closed. 
Muscular impressions two in each valve, the anterior one pro- 
duced into an elongated, ligulate band, the posterior short and. 
