8. IBLA. Four valves, one pair long, one pair short, peduncle hairy. Fig. 40. 9. BRISMEUS. Seven valves, even at the base. Fig. 38. 10. POLLICIPES. Principal valves in pairs, with many smaller valves at the base. This genus has been divided into _Pollicipes_, and _Capitellum_, the latter of which is founded upon Pollicipes Mitellus, Auct. Fig. 37 and 37*. PELAGUS. Montf. A genus composed of species of AMMONITES, which have the spire covered by the last whorl, as in Nautilus and have an umbilicus. ORBULITES. Bl. PELLUCID. Transparent. PELORUS. Montf. POLYSTOMELLA, Bl. A genus of microscopic Foraminifera. PELORONTA. Oken. NERITA _Peloronta_, Auct. Fig. 330. PENEROPLIS. Montf. A genus of microscopic Foraminifera. PENICILLUS. Brug. ASPERGILLUM, Auct. PENTALEPAS. Bl. PENTELASMIS, Auct. PENTAMERUS. Sow. ([Greek: Pente], _pente_, five; [Greek: meros], _meros_, part.) _Fam._ Brachiopoda, Lam.--_Descr._ Equilateral, inequivalve; one valve divided by a central septum into two parts; the other by two septa, into three parts; umbones incurved, imperforate.--_Obs._ Dalman remarks upon his genus Gypidia, that it is most probably identical with PENTAMERUS, Sow. but rejects the name for two reasons; 1st. That it has already been applied to a class of insects; 2nd. He disputes the fact of the shell being quinquelocular, i.e. not counting the triangular foramen in the hinge of the larger valve as one of the divisions. Fig. 212, 213. PENTELASMIS. Leach. ([Greek: pente], _pente_, five; [Greek: elasma], _elasma_, plate.) _Order._ Pedunculated Cirripedes, Lam.--_Descr._ Compressed, conical, composed of five valves; lower lateral pair sub-trigonal; upper lateral pair elongated, sub-quadrate; dorsal valve arcuate, peduncle elongated, smooth. Found on floating wood in the sea.--_Obs._ This genus is known from all others of the order by the number of valves. Pentelasmis is the genus Anatifera of Lamarck. Lepas anatifer, Linn. Fossil species of this marine genus are found in the Calcaire-grossièr of Paris, and in other similar beds. Fig. 34, P. lævis. PENULTIMATE WHORL. The last whorl but one. PERA. Leach. A genus composed of CYCLAS amnica, and other similar species. PERDIX. Montf. DOLIUM _Perdix_, Auct. PERFORATED. (_Perforatus._) Bored through, as the apex of Fissurella, fig. 245, and Dentalium, fig. 2. PERFORATION. (_Perforo_, to bore, or pierce.) A round opening, having the appearance of being bored, as in Haliotis, fig. 338. Sometimes the term is applied to an umbilicus which penetrates a shell through the axis to the apex, as Eulima splendidula, fig. 348. PERIBOLUS. Brug. A genus founded upon young specimens of CYPRÆA, with their outer lips not formed.