3 lit 



PILEOPSIS. 



PILULARIA. 



350 



HiffOttyf (Defrance). Animal oval or subclrcular, conical, or 

 depressed ; head globular, carried at the extremity of a sort of neck, 

 on each side of which is a tentacle convex at its base, and terminated 

 by a email conical point ; eyes placed on the tentacular convexity ; 

 mouth with two small labial tentacles ; foot very delicate, thickened 

 towards its borders, which lessen and enlarge like those of the mantle, 

 to which it bears a complete resemblance ; branchiae situated above 

 the origin of the back ; anus at the right side of the cervical cavity ; 

 oviduct terminated in a large tubercle at the root of the right 

 tentacle. 



Shell coneoid or depressed, the apex not spiral; aperture with 

 irregular edges ; cavity deep, with a muscular impression in the form 

 of a horse-shoe; a rounded lamellar support, or an impression on the 

 body serving as the resting-place of the animal, presenting also a 

 muscular impression of a horse-shoe shape. (Rang.) 



The number of living species given by M. Deshayes in his tables is 

 six; in the last edition of Lamarck the number is three : 11. acute, 

 H.foliacea, and II. tuturalis of M. Quoy ; the first from the seas of 

 Australia, and the last two from the island of Guam hi the archipelago 

 of the Marianne Islands. To these, according to his own showing, 

 Patella Australia should be added ; and also the Patella mitrata of 

 Linnaeus. 



The genus is marine, and has been found attached to stones and 

 shells at depths varying from the surface to 16 fathoms. 



//. acuta has the shell solid, ovate, thickly striated longitudinally, 

 the margin crenulated, violacescent ; the vertex long, acute, and 

 straight ; white internally. 



It is found in the seas of Australia. 



Hipponyx acitta, 

 a, the upper valve in situ ; b, -nsidc view of the same. 



Hipponyx acuta, var. 

 a, the animal ; fr, the shell in situ. 



Pileoptii (Lam., Capwlui, Montf.). Animal conical, slightly spiral 

 at the summit, furnished with a distinct head which has a proboscis 

 terminating the mouth ; in front of the anterior border of the foot 

 is a double membrane forming numerous folds ; the tentacles are 

 nearly cylindrical, stout, obtuse, and carry the eyes on small con- 

 vexities a little above their external base; foot large, but very 

 anterior and delicate ; mantle simple and without ornament ; branchial 

 cavity open anteriorly; branchiae composed of many narrow and 

 longitudinal lamina;, which adhere by a single transversal line to the 

 plafond ; orifice of the anus towards the right side of that cavity. 



Shell irregular, conical, with the apex more or less inclined or 

 spiral, directed backwards ; aperture rounded, with simple, irregular, 

 and continuous borders ; cavity deep, offering a muscular impression 

 in form of a horse-shoe, open anteriorly. (Rang.) 



This genus, like Hipponyx, is entirely marine, and has been taken 

 adhering to shells and stones at depths ranging from the surface to 

 20 fathoms. The Pacific, the East and West Indies, and the coasts of 

 Europe, are the localities principally known. 



The number of living species recorded by M. Deahayes in his 

 tables is seven, and of these one, Pileoptli Ungarica, is noted as 

 recent and fossil (tertiary) : the number given in the last edition of 

 Lamarck is six, to which, as we have seen, Patella Qalathea and P. 

 tricostata are to be added. 



P. Ungarica has the shell conico-acuminate, striated; the vertex 



fileofiit Vngarica. 

 a, toe shell in titu ; It, Inside ylcw of the ismc. 



uuciuate and revoluto ; aperture rather wider transversely ; rosy 

 within. The epidermis is somewhat horny, thick, and velvety. 



It is a native of the Mediterranean and the shores of the Atlantic. 

 Abundant on our own coasts. One of the best figures we know is 

 given by Mr. G. B. Sowerby in his ' Genera ' (No. xxxviii.) 



Fossil Hipponyces and Pileopsides. Lamarck has described some 

 fossil species among the PateUx under the name of P. Cornucopia, 

 and P. dilatata; and Mr. G. B. Sowerby (' Genera') states that all the 

 species known are from the Calcaire Grossier : (but see below). 



The number of fossil species (tertiary) recorded by M. Deshayes in 

 his tables is 12, and a 'new species' is noted as both living and 

 fossil (tertiary). The localities for these fossils are Sicily, Italy 

 (Sub-Ap.), Bordeaux, Dax, Touraine, and Turin. Paris is given as the 

 locality for eight. In the last edition of Lamarck six is the number 

 recorded, including Hipponyj; Cornucopia. 



Jlipponyx Cornucopia, 



a, external view of the upper valve ; b, internal view of the same ; c, inside 

 of lower valve. 



Pileoprit. Mr. G. B. Sowerby states that he is not acquainted with 

 many recent species, but that several are common among the fossils 

 of the tertiary beds. M. Deshayes, in his tables, gives the number of 

 fossil species (tertiary) as six, P. Ungarka being both recent and 

 fossil (tertiary, Baden) ; the other localities being Sicily, Italy (Sub-Ap.), 

 the English Crag, Bordeaux and Dax, and Touraine. 



Professor Phillips records Pikopsis (?) tritobus.* P. fylifer, P. 

 slriatiu, P. ncritoides, P. vetustus (?), and P. anyustus, from the 

 Mountain-Limestone Formation of Yorkshire and other districts. 

 (' Illustrations of the Geology of Yorkshire,' part ii.) 



Mr. Murchison, in his' catalogue of the shells of tho Middle Ludlow 

 Rock, records the only imperfect specimen yet obtained from the 

 Aymestry Limestone : the aperture appears less expanded than in 

 the Ptieopsii vetwsta of the Carboniferous Limestone. (' Silurian 

 System/) 



PILL-BEETLE. [BYRRmrs.] 



PILL-WORT. [PILULARIA.] 



PILOT-FISH. [CENTRONOTUS.] 



PILULA'RIA, a genus of Plants belonging to the natural order 

 Manileacete. Marsiteacece are creeping plants with alternate erect 

 leaves, having a circinate vernation; the fructification consisting of 

 globular, nearly sessile, coriaceous bodies, with three or four cells, and 

 containing sacs including either other bodies that germinate or loose 

 granules. [SALVINIACE/E ; SroROCABPiUM.] According to this defini- 

 tion it embraces only the genera Pilularia and Marsilea. The genus 

 Pilularia has solitary involucres, nearly sessile, globose, coriaceous, 

 4-celled; the cells containing bodies of two kinds, granules and 

 membranes containing minute grains. Of this genus there is but one 

 species, P. ylobulifera, which on account of the form of its fruit is 

 called Pill- Wort or Pepper-Grass. This plant is a native of Europe, 

 and is found hi Great Britain on tho extreme margin of ponds or on 

 swampy ground covered with water during the winter and compara- 

 tively dry in the summer. It is interesting to the systematic botanist, 

 as affording a high development in the organs of reproduction in the 

 class of Acrogens to which it belongs. The granules contained in 

 the cells ultimately become seeds, and have a very definite form of 

 germination. 



(Jussieu, Mfmoires de I' Academic Royale den Sciences; Valentine, in 

 the Transaction* of the Linnccan Society, vol. xriii.) 



I'ileopsia is generally considered to be feminine. 



