436 
CONCHIFERA. 
lower margin transverse, straight; beaks contiguous; hinge 
without teeth; ligament internal, placed in a triangular cavity. 
It has two sections—* ears equal or nearly so—** ears une¬ 
qual. 
Pecten varius. — The Speckled Pecten. 
Plate LXXXVIII. fig. 5. 
Ears very unequal; having about twelve ribs, covered with 
transverse prickly sub-erect scales, variously clouded and 
speckled with a variety of colours. Two inches and a quarter 
long. Inhabits the European seas. 
Genus 19.—PLAGIOSTOMA. — Lamarck. 
Generic Character. —Subequivalve, free, somewhat eared; 
base of the hinge transverse and straight; beaks remote ; hinge 
without teeth ; depression for the reception of the ligament coni¬ 
cal and partly internal. Species all fossil. 
Playiostoma spinosum.— The Thorny Plagiostoma. 
Plate LXXXVIII. fig. 6. 
Sub-arcuated, the umbo of one shell higher than that of the 
other, with longitudinal ribs, and remote concentric rings. 
Fossil. Britain. 
Genus 20.—LIMA.— Bruguiere. 
Generic Character.— Equivalve, with small ears; valves gaping 
at the sides ; beaks separate; cavity for the ligament partly exter¬ 
nal ; hinge without teeth. 
Lima vilrina. — The Glassy Lima. 
Plate LXXXVIII. fig. 7. 
Oblong-ovate; extremely pellucid, and pure snowy-white, 
with longitudinal distinct striae; lower margin denticulated. 
One half inch long. Inhabits the British seas. 
Genus 21. — PEDUM.— Lamarck. 
Generic Character .—Inequivalve, sub-eared; the lower valve 
tumid; beaks unequal, separate; hinge without teeth; ligament 
partly external, inserted in an elongated groove, in the internal 
