190 LTMKEUS. 



pennant. DiiFering sliglitly from Artemis in tlie hinge and 

 palleal sinus. See Sowerby's Thesaurus, PI. 13. 



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

 the form of a crescent. Applied most frequently to muscular 

 impressions. The word 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. 



LTJPOJS'IA. Grray, 1832. A genus composed of species of 

 Ctpe^a, Auct. which are described as having the anterior of the 

 eolumellar lip crossed by several irregular ridges, without any 

 distinct marginal ones, internally narrow, flat ; the sheU pear- 

 shaped, smooth, or cross-ribbed. Ex. C. Algoensis, Luponia 

 Algoensis, Grray, PL xxi. fig. 447. 



LTJTEAEIA. Lamarck. 1799. Xlutum ? mvA^—Fam. Mactra- 

 cea. Lam. Descr. Thin, equivalve, inequilateral, transverse, 

 oblong or ovate, gaping at both extremities ; hinge with one 

 double and sometimes one single cardinal tooth in each valve, 

 and a triangular, oblique pit with a prominent margin, contain- 

 ing the ligament ; muscular impressions distant ; palleal impres- 

 sion having a large sinus. — Ohs. This genus differs from Mactra 

 in the entire absence or indistinctness of lateral teeth. Pig. 77, 

 L. Papyracea. (Ligula, Leach.) Pig. 78. L. Solenoides. Sandy 

 and muddy shores. PL iii. fig. 77, 78. 



LUTEICOLA. BlainviUe, 1825. Ltttraeia. Lam. 1799. Pig. 

 77,78. 



LYCOPHEIS. Montf. A microscopic fossil described as resem- 

 bling NuMMTJLiTES, but having a granulated surface. 



LTMNADEA. Sw. A sub-genus of " My sea," Turton, in the 

 family of Nayades, Lam. thus described : " Posterior hinge 

 margin elevated and winged ; the valves connate ; the surface 

 smooth. L. alata Sw. Ex. Conch, (fig. 48.) fragilis. Sw. Zool. 

 111. compressa. Lea. Am. Tr. iii. pL 12. f. 22." Sw. p. 379. 



LTMNEA. See Limnea. 



LTMNEIJS. Lam. See Limneana. 



