I'APYIUDEA. 215 



PANDORA. Brug. Fam. Corbulacea, Lam. Pyloridea, Bl. — 

 Descr. Thin, inequivalve, pearly within, rounded anteriorly, 

 rostrated posteriorly ; right valve flat with a cardinal tooth, 

 or short rib, and a slit containing the cartilage with a narrow 

 plate on the dorsal edge turned towards the left valve ; left valve 

 concave, with a receptacle for the cardinal tooth of the right valve 

 and the internal cartilage ; no external ligament. Europe, Ame- 

 rica, Ceylon, &c. — Obs. This well known genus is in no danger 

 of being confounded with any other shell. Fig. 90. P. rostrata. 



PANOPiEA. Menard. Fam. Solenacea, Lam. Pyloridea, BL— 

 Descr, Equivalve, inequilateral, oval, gaping at both extremities; 

 hinge with an acute cardinal tooth in each valve, and a large cal- 

 losity near the umbones supporting the ligament ; muscular 

 impressions two, distant, oval ; palleal impression with a large 

 sinus, Britain, North America, Mediterranean, Australia, &c. — 

 Obs. This genus resembles Mya in general appearance, but 

 differs in having an external ligament and a sharp tooth, in- 

 stead of the broad spoon-shaped process in the hinge of the latter 



' genus. Fig. 65. P. Australis. 



PAPER SAILOR. A common name given to the Argonauta. 



PAPILLARY. {Papilla, a teat.) Shaped like a teat. This term 

 is applied by conchologists when the apex of the spire of an uni- 

 valve shell is rounded like a teat and not spiral up to the extreme 

 point ; as the apex of Cymba, fig. 434. 



PAPYRACEOUS. {Papyrus, a kind of paper made of the flags of 

 the river Nile in Egypt.) Of a thin, light texture, resembling 

 that of paper. An example of this is to be seen in the Argonauta, 

 commonly called the " Paper Sailor," fig. 485, and in the Pholas 

 papyracea, fig. 56. 



PAPYRIDEA. Sw. A sub-genus of Cardium, thus described ; 

 " Shell heart-shaped, or transversely oval ; inequilateral ; the 

 anterior side almost always gaping ; representing the Pholidse. P. 

 Soleniforme, Wood, Conch, pi. 56. f. 3. — apertum, lb. 56. 

 f. 2. — transversum, Sow. Conch, f. 4. — ringens, Wood, pi. 53. 

 f. 1, 2. 



