LUPONIA. 179 



LOTORIUM. Montf. A genus composed of species of Triton, 



Auct. in which the aperture is effuse. T. Lotorium, fig. 400. 

 LOTH A. Gray. Patelloida, Quoy and Gaimard. 

 LUCERNA. Humph. A generic name applied to some species of 

 Helix included inDe Ferussac's sub-genus Helicogena. 



LUCERNELLA. Sw. A genus of " Lucerninse," Sw. thus des- 

 cribed: " Teeth on both sides of the aperture; surface regularly 

 and distinctly striated. Circumference convex." 



LUCIDULA. Sw. A sub-genus of Lucerna, Humph, thus described : 

 " Aperture transverse, both lips much thickened and united; the 

 outer with marginal obsolete teeth at the base; umbilicus closed. 

 Barbadensis, Lam. No. 49. p.78. Fer. Moll. pi. 47, 2, 3, 4." 



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 exter- 

 nal, 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 

 semi -rotund; impression of the mantle not sinuated. — 06s. The 

 shells of this genus resemble Amphidesma in general form, but 

 are distinguished by the external ligament, the elongated mus- 

 cular impression, and the want of a sinus in the palleal impres- 

 sion. East and West Indies, and European shores. Fig. 104, 

 L. Tigerina. 



LUNULATE. (Luna, the moon, dim.) Moon-shaped, having 

 the form of a crescent. Applied most frequently to muscular 

 impressions. Semilunar is sometimes used, perhaps with greater 

 accuracy, to express the same shape. 



LUNULE. An impression on the anterior dorsal margin of some 

 bivalve shells. The similar impression on the posterior dorsal 

 margin is called the escutcheon. 



LUPONIA. Gray. A genus composed of species of Cvpr^ea, 

 Auct. which are described as having the anterior of the columellar 

 N 2 



