AMPLEXUS. 



03 



anomaly which is considered hy Mr. G. B. Sowerby, sen., as merely 

 accidental. They resemble the Ammonites in internal structure, 

 but instead of being spirally convolute they are merely curved like 

 a horn. Ex. fig. 477, copied from De Blainville. 



AMNICOLA. The name of a genus mentioned in the family of 

 Melaniana in the conchological part of the Synopsis of the British 

 Museum, but unexplained. 



AMPHIBOLA 1 The same as Ampullaria, Auct. 



AMPH1BULIMA. Lam. Succinea 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 aban- 

 doned by its author, and the species stands in his system as Suc- 

 cinea cucullata. West Indies. 



AMPHIDESMA. Lam. (from Afi^o), ampho, ambo, Aeafioc, desmos, 

 ligamentuni). Fam. Mactracea, Lam. — Bescr. 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 exca- 

 vation of the hinge. — Obs. 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 distinct 

 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. Reticidatum, 

 fig. 85. West India Islands, Brazil, Coast of Pacific, &c. 



AMPHIPEPLEA. Nilson. The type of this proposed genus is 

 Limnea glutinosa, Auct. Gray's edition of Turton, page 243, 

 plate 9. fig- 103. The shell is polished and the inner lip expanded. 



AMPHISTEGINA. D'Orb. A genus of microscopic Foraminifera. 



AMPLEXUS. J. Sowerby. A. Corralloides, fig. 463. A singularly 

 formed fossil, described as nearly cylindrical, divided into cham- 



