64 AMPLEXUS, 



AMPHIBOLA. Scliuin. 1817 ? A genus formed for the shell 

 usually named Ampullaria avellana, fig, 538. 



AMPHIBULIMA. Lam. 1812. Suocinea Patula, Auct. (fig. 

 266) was first published in the Ann. du Mus. D'Hist. Nat. 

 under the name Amphibulima cucullata. The generic name was 

 afterwards abandoned by its author, and the species stands in 

 his system as Succinea cucullata. "West Indies, PI, xiii. 

 fig. 266. 



AMPHICEEAS. Gronovius, 1781. Ovula, Bruguiere; Ovijlum, 

 Sowerby. 



AMPHIDESMA. Lam. (from Aju^w, ampho, ambo, AEo-juog, desmos, 

 ligamenfMm). Farm. Mactracea, Lam. — JJe^cr. Equivalve, oval or 

 rounded, sub-equilateral, sometimes rather gaping at the sides, 

 with slight posterior fold; hinge with one or two cardinal teeth 

 in each valve, and two elongated lateral teeth, distinct in one 

 valve, nearly obsolete in the other ; ligament short, separated 

 from the cartilage, which is elongated and couched obliquely 

 in an excavation of the hinge. — Ohs. In most bivalve shells, the 

 cartilage and ligament are united in one mass, or placed close 

 to each other ; the contrary in this case gives rise to the name, 

 which signifies double ligament. This circumstance distinguishes 

 the genus Amphidesma from Tellina, which in other respects it 

 greatly resembles. From Lutraria it may be known by its dis- 

 tinct lateral teeth, and also by its valves being nearly close all 

 round, while the Lutrarise gape anteriorly. The species do not 

 appear to be numerous ; no fossil species are known. A. Reti- 

 culatum, fig. 85. West India Islands, Brazil, Coast of the 

 Pacific, &c. PL iv. fig. 85 ; PI. xxiv. fig, 495. 



AMPHIPEPLEA. Nilson, 1822. The type of this proposed 

 genus is Limnea glutinosa, Auct. G-ray's edition of Turton, 

 page 243, PI. ix. fig. 103. The shell is polished, and the inner 

 lip expanded. 



AMPHISTEGINA. D'Orb. A genus of microscopic Forami- 

 nifera. 



AMPLEXIJS. J. Sowerby. A. Corralloides, fig. 463. A singu- 

 larly formed fossil, described as nearly cylindrical, divided into 



