CONCHIFERA. 
435 
TRIBE II.-PECTINIDES. 
Shell for the most part regular, and not foliaceous •, the liga¬ 
ment either interior, or partly so. 
Genus 15. — PODOPSIS.— Lamarck. 
Generic Character. —Inequivalve, nearly regular, adhering by 
its lower beak; without ears; the lower valve the largest, con¬ 
vex, and produced at the base; binge without teeth; ligament 
internal. Fossil. 
Genus 16—SPONDYLUS.— Linnceus. 
Generic Character. —Inecpiivalve, adherent, eared, spined, and 
rough, with unequal beaks ; lower valve with an external longi¬ 
tudinal groove, which increases with the age of the animal; 
hinge with two very strong hooked teeth in each valve, and a 
central cavity for the ligament, communicating at its base with 
the external groove; ligament internal. 
Spondylus longispina. — The Long-Spined Spondylus. 
Plate LXXXVIII. fig. 2. 
Longitudinally sulcated and ribbed, thickly spined ; of a red¬ 
dish colour ■, alternate spines, arcuated and tongue shaped; urn- 
bones orange. Four inches long. Inhabits the Indian ocean. 
Genus 17.—PLICATULA.— Lamarck. 
Generic Character. —Inequivalve, without ears, attenuated at 
the base, rounded and plaited at the upper margin; beaks une¬ 
qual arid entire; hinge with two strong teeth in each valve, 
with a central cavity for the ligament, which is internal. 
Plicatula ramosa. — The Branched Peicatijla. 
Plate LXXXVIII. fig. 4. 
Oblong, trigonal, very thick ; with strong longitudinal plaits; 
brown, or yellowish-brown, with rust-coloured, arrow-shaped 
markings; inside white. One inch and a half long. Inhabits 
the American seas. 
Genus 18.—PECTEN.— Lamarck. 
Generic Character. —Free, regular, inequivalve, eared; the 
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