PAPYRIDEA. 215 



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

 Bescr. Thin, ineqnivalve, 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 — 

 Bescr. 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. — trans versum, Sow. Conch, f. 4. — ringens, Wood, pi. 53. 

 f. 1, 2. 



