86 POLYMORPHINA. 
impressions one in each valve. Obs. The cardinal teeth, resem- 
bling those of Spondylus, distinguish this genus from other 
Ostracea. Fig. 178, P. gibbosa. 
PNEUMONOBRANCHIA. Lam. The second section of the 
order Gasteropoda, Lam. containing the family Limacinea, fig. 
256 to 263. 
PODOP’SIS. Lam. This genus appears to have been described 
from specimens of a species of Spondylus, with the triangular 
disc broken out so as to present a similarly shaped foramen, 
which was supposed to afford a passage for a large byssus. 
POLINICES. Montf. A genus composed of Natica mammilla, 
and other similar species, with mammillated spires, and the um- 
bilicus filled with enamel. Fig. 327. 
POULIA. Gray. A genus proposed to include several species of 
shells belonging to the Canalifera of Lamarck. They differ 
from Triton in having no external varices; from Purpura, in 
having crenulated columelle. The inner edge of the outer-lip 
is also crenulated. Fig. 415. P.articulata, Fusus. Lam. Triton 
undosus, Lam. belongs to this genus. 
POLLI'CIPES. Auct. (Poller, a thumb’s breadth; pes, a foot.) 
Order. Pedunculated Cirripedes, Lam. Descr. Conical, compressed 
consisting of numerous valves, mostly in pairs, three or four 
pairs forming the principal part of the shell, and surrounded at 
the base by two or three rows of smaller valves, supported on a 
scaly, short pedicle. Obs. This description will be found to ex- 
clude Scalpellum and Smilium, the valves of which are more 
equal. The P. Mitellus, Auct. (fig. 37*) has been separated 
asa genus Mitellus by some authors, and it certainly is very 
different from P. polymerus, Fig. 37, and P. cornucopia. 
POLLON’TES. Montf. Miutona, Bl. A genus of microscopic 
Foraminifera. 
POLYBRANCHIA'TA. Bl. (Hodvs, many; Branchie, gills.) 
The fifth family of the order Lammellibranchiata, Bl. contain- 
ing the genera Arca, Pectunculus and Nucula, which have a 
series of small teeth on the hinge. 
POLYDON’TES. Montf. (Modus, polws, many ; odos, odos, tooth.) 
A species of Helix, shaped like Carocotta, and having a number 
of teeth in the aperture. 
POL.YGONUM. Schum. (Modus, polus, many; yera, gonia, an 
angle.) A genus composed of species of Tursivetius, Auct. 
which have large, continuous cost#, so as to present the ap- 
pearance of many sided shells. TT. polygonus, fig. 383. 
POLYLE’PAS. Bl. (Hodvs, polus, many; demas, lepas, Linn.) 
ScaLpetium, Auct. 
POLY’LEPAS. Klein. Coronuta Diadema, Auct. 
POLYMORPHINA. D’Orb. A genus of microscopic Forami- 
nifera. 
