78 PEDIPES. 
grooved, striated or banded, radiately. Cbs. Lottia differs from 
Patella in the construction of the animal; SrepHoNARIA, in the 
lateral siphon; and Ancy.us, in the oblique twist of the axis, as 
well as in the nature of the animal. The Patellz are marine. 
Fig. 229. 
PATELLIFORM. (Patella, a dish; forma, shape.) Shaped like 
a dish. 
PATEL'LOIDEA. Bl. The third family of the order Monopleu- 
robranchiata, Bl. containing the genera Umbrella and Sipho- 
naria. 
PATEL‘LOIDES. Quoy and Gaimard. Lorri, Gray. 
PAVONIA. D’Orb. A genus of microscopic Foraminifera. 
PAX’YODON. Schum. Hyri, Lam. 
PEC’TEN. Brug. (Acomb.) Fam. Pectenides, Lam. Subostracea, 
Bl. Deser. Inequivalve, ribbed longitudinally, nearly equila- 
teral, with a triangular auricle on each side of the umbones ; 
hinge linear, destitute of teeth, having a central pit containing 
the cartilage; muscular impressions one in each valve, large, 
sub-central. Obs. This genus of beautiful shells, to which the 
well-known Scallop belongs, contains numerous species, some of 
which are found in the British seas. The Hinnites Pusio. P. 
Pusio of some authors, has been separated on account of the ir- 
regularity of the external surface of one valve. Fig. 171 to 173. 
PEC’TINATED. (Pecten, a comb.) Marked in a regular series 
of ridges. 
PEC’TENIDES. Lam. A family belonging to the second section 
of the order Conchifera, Dimyaria, Lam. containing the genera 
Pedum, Lima, Plagiostoma, Pecten, (including Decatopecten 
and Hinnites,) Plicatula, Spondylus and Podopsis. 
PECTUN’CULUS. (Pecten, dim.) Fam. Arcacea, Lam. and Bl. 
Descr. Equivalve, sub-equilateral, orbicular, thick, covered with 
a velvety epidermis, striated longitudinally; ventral margin 
denticulated within; hinge semi-circular, with a series of small 
teeth on each side of the umbones, which are separated by a 
small triangular disc in each valve bearing the ligament; mus- 
cular impressions two in each valve, strongly marked, united 
by an entire palleal impression. Obs. The characters of this 
genus are so strongly marked that there is no danger of con- 
founding it with any other. It does not contain many species; 
two or three are British. The fossil species occur in London clay 
and Calcaire-grossiér. Fig. 134, P. pilosus. 
PEDIPES. Adanson. Fam. Auriculacea, Bl.; Colimacea, Lam. 
Descr. Sub-globose, longitudinal, thick, striated; spire equal to 
aperture in length; aperture sub-ovate ; peritreme sharp, thick- 
ened within, modified by the last whorl; columella with three 
strong plaits on the inner edge; outer lip with one fold. Obs. 
This genus contains but one or two small, recent species, which 
