234 PEDUNCLE. 



system of Lamarck " Pedunculated Cirripedes," consisting of a 

 fleshy tendinous tube, by the lower end of wliicb they are 

 attached to sub-marine substances. 



PEDICIJLAEIA. Sw. A genus of " Scutibranchia," thus de- 

 scribed : " Shell irregular, sub-patelliform ; a thick, large, 

 obsolete apex on one of the longest sides, and an internal cal- 

 lous rim within, on one side only ; circumference undulated, 

 irregular. P. Sicula, Sw." Sw. p. 357. Sicily. A singular 

 shell probably of the nature of the Cyprsedse, which is found 

 attached to corals, conforming its shape to the irregularity of 

 their surface, and fitting closely. Ex. PI. xxiv. Pig. 513. 



PEDIPES. Adanson, Fam. Auriculacea, Bl. Colimacea, Lam. 

 — Bescr. Sub-globose, longitudinal, thick, striated ; spire equal 

 to the aperture in length ; aperture sub-ovate ; peritreme sharp, 

 thickened 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, in some respects resembling Auricula, from which it is 

 known by the thickness of its shell, and its globular form. 

 Coast of Africa. PL xiv. Fig. 299, P. Adansoni. 



PEDUM. Lam, {A shepherd's crook.) Fam. Pectinides, Lam. 

 Sub-ostracea, Bl. — Descr. Irregular, inequivalve, sub-equilateral, 

 attached 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-orbicular ; both valves fiat, narrow at the dorsal, broad at 



. the ventral extremities ; lower valve with raised edges over- 

 wrapping the upper, — Obs. This singular genus, of which only 

 one species is known, differs from aU the other Pectinides, not 

 only in shape and structure, but also in the mode of attachment, 

 which is by means of a byssus passing through a sinus in the 



. lower valve; and not, as in Ostrsea, by a part of the outer sur- 

 face. P. Spondyloideum is the only species at present known. 

 Moluccas.. PI. X. fig. 179. 



PEDUNCLE. See Pedicle. 



