PENTELASMIS. 79 
in some respects resemble Auricula, from which it is known by 
the thickness of its shell, and its globular form. Fig. 299, P. 
Adansoni. 
PE’DUM. (A shepherd’s crook.) Fam. Pectenides, Lam. Subos- 
tracea, Bl. Descr. Irregular, inequivalve, sub-equilateral, at- 
tached by a byssus passing through a sinus in the lower valve ; 
hinge toothless, with a triangular area in each valve, separating 
the umbones; ligament contained in a groove running across the 
area; muscular impressions one in each valve, large, sub-orbi- 
cular; both valves flat, narrow at the dorsal, broader at the ven- 
tral extremities; lower valve with raised edges overwrapping 
the upper. Obs. This smgular genus, of which only one species 
is known, differs from Ostreea, not only in shape and structure, 
but also in the mode of attachment, that is by a byssus. Fig. 
179, P. Spondyloideum. 
PEDUN’CULATED. (Pedunculus, a little foot.) Attached to 
external objects by a hollow fleshy tube, called the Peduncle. 
PEDUN’CULATED CIRRIPEDES. Lam. An order consisting 
of molluscs which have multivalve shells, supported on a Pedun- 
cle; containing the genera Anatifer, Pollicipes, Cineras, Otion. 
PELAGUS. Montf. Composed of species of Ammonitzs, which 
have the spire covered by the last whorl, as in Nautilus, and 
have an umbilicus. Orsuuirss, Bl. 
PELO’RUS. Montf. Potysrometia, Bl. A genus of microscopic 
Foraminifera. 
PELORON’TA. Oken. Nerira Peloronta, Auct. Fig. 330. 
PEN’EROPLIS. Montf. A genus of microscopic Foraminifera. 
PENICIL’LUS. Brug. AspEreitium, Auct. 
PENTALE’PAS. Bl. Penrenasmis, Auct. 
PENTA’MERUS. Sow.(Hevre, pente, five ; uepes, meris, part.) Fam. 
Brachiopoda, Lam. Deser. 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 Gypidium, that it is most pro- 
bably identical with Penramerus, Sow. but rejects the name 
for two reasons; Ist. That it has already been applied to a class 
of insects; 2nd. He disputes the fact of the shell being quinque- 
locular, i. e. not counting the triangular foramen in the hinge of 
the larger valve as one of the divisions. Fig. 212, 213. 
PENTELASMIS. Leach. (Mere, pente, five; edasya, elasma, 
plate.) Order. Pedunculated Cirripedes, Lam. Descr. Com- 
pressed, conical, composed of five valves; lower lateral pair 
sub-trigonal; upper lateral pair elongated, sub-quadrate; dorsal 
valve arcuate; peduncle elongated,smooth. Obs. This genus is 
known from all other genera of the order by the number of 
valves. Pentelasmis is the genus Anatifera, Lam. Lepas ana- 
tifer, Linn. Fossil specimens of this marine genus are found 
