PATELLA. TE 
PANDORA. Brug. Fam. Corbulacea, Lam. Pyloridea, Bl. Deser. 
Thin, inequivalve, pearly within, rounded anteriorly, rostrated 
posteriorly; right valve flat, with two posterior ribs and a nar- 
row plate turned towards the opposite valve; left valve concave, 
destitute of distinct teeth, with a receptacle for the cardinal 
tooth and posteriorly elongated rib of the right valve; ligament 
internal. Obs. This well known genus is in no danger of being 
confounded with any other shell. Fig. 90, P. rostrata. 
PANOPA’A. Fam. Solenacea, Lam. Pyloridea, Bl. Descr. Equ’ 
valve, inequilateral, oval, gaping at both extremities ; hinge with 
an acute cardinal tooth in each valve, and a large callosity near 
the umbones supporting the ligament; muscular impressions 
two, distant, oval; palleal impression with a large sinus. Obs. 
This genus resembles Mya in general appearance, but differs in 
having an external ligament and a sharp tooth, instead of the 
broad spoon-shaped process in the hinge of the latter genus. 
Fig. 65, P. australis. 
PANTASTERA. Pentamerus. Sow. 
PARACEPHALOPH'ORA. Bl. The second class of the type 
Malacozoaria, Bl. divided into the sub-classes: P. dioica, P. 
monoica, P. hermaphrodita. 
PAR’TULA. Fer. Fam. Colimacea, Lam. Auriculacea, Fer. 
Deser. Conical, smooth; spire equal to aperture in length, con- 
sisting of few whorls; aperture auriform; outer lip reflected, 
broad ; inner lip reflected, with a slight prominence on the colu- 
mella. P. australis, fig. 302. 
PARMACEL'LA. Cuv. (A little cell.) Fam. Limacinea, Lam. & 
Bl. Deser. Haliotoid, internal, thin; spire flat, consisting of one 
or two rapidly increased whorls; aperture as large as the whole 
shell, with the dorsal margins inflected. Obs. This description 
applies to Parmacella of Cuvier. The shell figured in Sowerby’s 
genera is Cryptella of Webb. Fig. 257, P. Olivieri; Fig. 258, 
P. Palliolum. 
PARMOPHO’RUS. Lam. <A genus composed of Emarginula 
elongata, Auct. and other species of a similarly oblong form. 
Fig. 242, P. elongatus. 
PASITHAA. Lea. A genus formed of some pyramidal shells, 
described as resembling Melania, but separated from that genus 
on account of being marine fossils. Fig. 317, P. striata. 
PATELLA. Linn. (A dish or platter.) Fam. Phyllidia, Lam. 
Retifera, Bl. Descr. Symmetrical, compresso-conical, nearly 
regular, oblong or oval; apex sub-central, inclining towards the 
anterior margin; aperture oval, forming the base of the shell; 
internal surface smooth ; with a muscular impression shaped like 
a horse-shoe, with the ends bending forwards, encircling and di- 
viding the space all round, except where the interruption occurs, 
to receive the head of the animal; external surface ribbed, 
