141 



PKCTtTNCCLUa 



PBDKJULUa 



.a 



out iato MI external, Irregular, somewhat longitudinal superficial 

 Awn*, or dcatrix. which U narrowest at the hinge margin, and which 

 il raUnlr fiiU to levrl with the nurrounding surface of the ihelL 

 (Brodcrip. ZooL Proc.,' February 1831) 



Th. pccim of this mom are widely diflWd. and inhabit the MM 

 of wmnn climate* in both hemisphere*. Mr. Broderip bu deKribed 

 four (' ZooL Proe.' and Muller SynopBi') brought to thi* country by 

 Mr. Cumin* from the We* Indie*, Central America, and other wertem 



oalitiY* "They 



j wer dredged from sandy mud and muddy bottoms, 

 adhering to bivalve (hells, dead and living, and dead coral, at depth* 

 of , 11, and 17 fathom.; of the*. Plaarnu tckimata wears something 

 of the appearance of the abort .pined Spmdyti. Beside* the ipecie* 

 above alluded to, Mr. Broderip state* that Mr. Sowerby furnished him 

 with an odd valve of a large species from Lnconia, which wa* beauti- 

 fully iride*ent internally ; but a* it wa* believed that this was iden- 

 tical with the fine shell sold by him to the British Museum, Mr. Broderip 

 left the description of it to the officer* of that establishment Mr. 

 Oowabj had some other odd valves, which Mr. Broderip thought 

 might prove new, and the latter possessed two or three specimens 

 adhering to Oftodfti, from an unknown locality ; but they appeared 



M. Deahaye* remarks that this genus establishes the passage between 

 Ptocma and A*omia, and that it shows that the V-shaped tooth of 

 a i* only an extreme modification of the large callosity of the 

 i; he add* that a fossil shell found in Egypt, and which has 



been taken for a f lacuna, is a new step, as regards the hiuge, between 

 the Amomicf and Placmue. 



P. Cumimyii (Brod.) has the shell snbround, obscurely silvered, 

 white, flattened ; margin plaited, the plaits very large ; length 2 4 inches, 

 breadth 7-10ths of an inch ; height 2] inches. 



It inhabits the shores of Central America (Oulf of Dulce, Province 

 of Costa Rica) ; dredged from a muddy bottom, at the depth of 

 11 fathoms, attached to dead bivalve shells and dead coral 



riartauMomia Oumiitfii. 

 a, lattrul ppesrinee of the ortu of adhnion ; b, the same Been externally. 



PECTUNCULUS. [PoiTODOHTA.] 



I ' ) : 1 1 A MACK.*', a natural order of Monopetalous Exogenous Plants, 

 very nearly related to VtrbauKta, having like it irregular and usually 



1 2 



*7'.ti' / ! W 'if l<< * fa V* <rW ' ' * I. corolla laid ojtn ; t, ihs 

 ; I, the tip* halt ; 4, a IruumM HeUon of (be latter. 



didynamous flowers and a few-seeded 2- or 4-celled fruit ; but differing 

 in having the radicle directed towards the base instead of the apex of 

 the fruit. From Bignoniacttr, with which they are more generally 

 compared, their winglrss seeds oner the principal distinction. They 

 are all exotic tropical herbaceous plants, with opposite leave* and 

 axillary flowers, and are of little krown use, with the exception of 

 the genus Stimmum, whoae seeds afford a bland oil not inferior, when 

 fresh, to that of the olive. [Sis A MUM.] 



Uncaria procumbent, the Grapple Plant of the Cape of Good Hop, , 

 has the fruit covered with curved spines, which lay hold of the clothes 

 of travellers. The horns of Martynia probotcidea do the same, and 

 are called in Italy the Testa di Quaglia (Quail's Head). The order 

 contains 14 genera and about 25 species. 



PE PETES. [MURIDJL] 



PEDIASTRUM. [DwiODiEAl 



PEDICEL. rPEDOKCLE.] 



PEPICELLARIA, the name given by Muller to little pincer-shaped 

 bodies found on the surface of many species of star-fishes and sea- 

 urchins. When seen on the surface of the dried specimens they appear 

 like little cleft spines. In I'rtuter rubtnt, according to Dr. Sbarpey, 

 they cover the surface generally, and are more numerous round the 

 spines. Each one of those little bodies consists of a soft stem, which 

 bears on it* summit a little forceps of calcareous matter. If anything 

 is iatroduced between the blades of these forceps when the animal is 

 alive, it is instantly grasped with considerable force. Those on the 

 body and upper spines differ in shape from those on the spines imme- 

 diately bordering the avenues. When the starfish is living the blades 

 of the forceps are in continual activity, but when cut off they seem to 

 lose that power. These bodies have been observed by Sars in Echinut 

 ipkara, and he describes three species P. tridtnt, P. triphyUa, and 

 P. glob if era. 



The question of the nature of these bodies has been often agitated. 

 Whilst Muller and others have considered them to be parasitic animals, 

 Oken, Sharpey, and Sars regard them as organs of the animal Sars 

 assigns the following reasons for his belief : 



1. The PediceUaria are found in the same species of Echinodermata 

 under all circumstances, which would not be the case if they were 

 parasitical animals. 



2. The structure of the calcareous forceps and stems to which they 

 arc attached, bear structurally a greater resemblance to the spines of 

 the Echinodermata than to other structures. 



3. The PediceUaruc have a vital connection with the skin and shell 

 of the Echiniu. The stem of the Pedicel/aria ia attached to a knob 

 of the shell of the Echima, on which it moves. 



4. Sars states that when a single Pedicellaria is irritated, the rest 

 are inclined towards it 



Although Professor E. Forbes states that he was not able to confirm 

 Sars's observation on the two last points, he was nevertheless inclined 

 to adopt the opinion that they were peculiar organs of the Echino- 

 dermata, rather than parasitic animals. 



(E. Forbes, Brituh. Star-Puhtt.) 



PEDICULATUS (from the Latin word Pedicvlui, a louse, from its 

 supposed quality of making sheep that feed upon it lousy), a genus 

 of Plants belonging to the natural order Scrophularacea. It has an 

 inflated 6-toothed calyx, a ringent corolla, with the upper lip laterally 

 compressed, the lower plane, 3-lobed; the capsules are acute and 

 compressed; the seeds numerous and angular. The species are 

 usually simple herbs. The flowers senile, disposed in dense terminal 

 interrupted spikes. 



P. /.a/uxf n't. Marsh Louse- Wort, has a solitary erect stem, branched 

 throughout, pinnatifid leaves, with oblong blunt-lobed segments ; on 

 ovate pubescent 2-lobed calyx, the lobes incise, dentate, crisped. The 

 upper lip of the corolla has a short truncate beak, with a triangular 

 tooth on each side. The flower is large and crimson, varying to white. 

 It is found In marshes and wet meadows, particularly in the north of 

 England, and is said to be injurious and disagreeable to cattle. This 

 i the Pedicularit Jlerba of Columella, vi. 30, and of Scribonius 

 Largus. 



P. tylvalica, Wood Louse-Wort, has a stem branched at the base, 

 erect, the branches long, spreading, and prostrate ; the leaves pinnatifid, 

 leaflets ovate and deeply toothed. The upper lip of the corolla as in 

 the last species, the flower large and rose coloured. It is found on 

 wet, hrathy, and rather hilly grounds in Siberia, Europe, and Great 

 Britain. The expressed juice of the herb, or a decoction, has been 

 used with advantage as an injection in serous ulcers. It is injurious 

 to the sheep that feed on it There are 75 other species of Ptdtcularit 

 enumerated, none of which are British, or applicable to any useful 

 purpose. They ore found chiefly in Europe and Northern Asia. 



(Habineton, Manual of Britith Botany.) 



PKPI'CULUS (Linnaius), a genus of Insects belonging to the order 

 Aptrra. These insects, commonly called Lice, form the order A noplura 

 of Pr. I*ach, and Paratita of Latreille. [Awori-rnA.] Latreille thus 

 characterises this order of insects : Their body is flattened, newly 

 diaphanous, and divided into 11 or 12 distinct segments, of which 

 three belong to the trunk (or thorax), each bearing one pair of legs. 

 The first of these segments frequently forms a sort of thorax (or 

 rather prothorax). The stigmata are very distinct The antenna; are 

 short, equal, composed of five joints, and frequently inserted in a 



