215 



PEDILANTHUS. 



PELABGONIUIT. 



249 



notch. There are one or two small ocelli on each side of the head. 

 The legs are short, and terminated by stout claws, or two opposing 

 hooks, which enable these animals to cling with great facility to the 

 hairs of quadrupeds or the feathers of birds, whose blood they suck, 

 and on whose body they propagate and pass their lives. They attach 

 their ova to these cutaneous appendages, and multiply excessively, one 

 generation succeeding another with great rapidity. Particular and 

 unknown causes facilitate their increase to an astonishing degree, the 

 P. humanut, under such circumstances, producing in man what is 

 termed the ' morbus pediculosus.' Their movements are slow. 



Three species of Lice are said to infest the human subject the 

 P. humanui, which inhabits the bodies and garments, and is known 

 by the name of the Body-Louse; the P. cervicalit, or P. humanus 

 capitis of De Geer, which inhabits the head of man, and particularly 

 children ; and lastly, the P. pubis of Linnaeus, which constitutes 

 Leach's genus Phthina. This species inhabits the eyebrows, &c., and 

 is commonly known by the name Crab-Louse. 



The following are the principal genera into which the Pediculi are 

 divided : 



In Pedicului proper the mouth, which is in the form of a snout, 

 consists of a very small tubular mammilla situated at the anterior 

 extremity of the head ; the tarsi are composed each of a joint almost 

 equal in size to the tibia, and terminated by a strong claw, which 

 folds over a projection, and fulfils the function of a forceps; the 

 thorax is composed of three distinct equal segments. The P. humanut 

 and P. Cfrricalis belong to this genus. 



The genus Phthinu differs from Pediculiu in having the body wide 

 and rounded, the thorax very short and confounded with the body : 

 the anterior feet are simple, and the two hinder pairs are didactyle. 



The Pediculiu of the Hog has the thorax narrow and distinct from 

 the abdomen, which is very broad ; it constitutes, according to Leach, 

 the genus Hcematopwui. 



The Nirmi (Nirmu* of Hermann, Leach, &c., and Ricinui of De 

 Geer) have the mouth situated beneath the head, and composed of 

 two lips and two hook-like mandibles ; their tarsi are very distinct, 

 and terminated each by two equal hooks. Latreille says that the 

 species of this group, with one exception, that of the dog, are exclu- 

 sively confined to birds. 



PEDILANTHUS, a genus of Plants belonging to the natural order 

 Euphorbiacea;. It has a common slipper-shaped involucre. The male 

 flowers several in the circumference. Pedicels bracteolate, each arti- 

 culated with a naked anther. Female flowers one in the centre. 

 Calyx wanting ; style 1 ; stigmas 3 ; capsules 3-coccus. 



P. tithymaloides, Jew-Bush, is found in various parts of the West 

 Indies in stony bushy places, near the coast. It in a shrub throwing 

 out runners, erect, about six feet high, abounding in white bitter milk. 

 The items are numerous, weak, soft, as thick as the finger ; when old 

 cinereous, when young green. The leaves are ovate, obtuse, or acute ; 

 coriaceous, entire, alternate, stalked, distichous, when young downy 

 on each side, and wavy at the edges, becoming at last quite smooth 

 and flat. Peduncles 1-flowered, short, clustered about the extremities 

 of the branches. Involucre slipper-shaped, bright-red with a green 

 back. The practitioners of Curacoa give a decoction of the whole 

 plant, especially of the stem, as the ordinary beverage, and in large 

 doses in some diseases. The root is emetic. 



(Lindley, Vegetable Kingdom ; Lindley, flora Medico.) 



PE'DIPES (Adanson), the name for a genus of Turbinated Molliuca 

 belonging to the family Auriculacca of M. De Blainville and Colimacea 

 of Lamarck. 



PEDUM. [PECTINIDJ:.] 



PEDUNCLE, the stalk of the flower in Plants. The secondary 

 talks are called Pedicels. [INFLORESCENCE ; FLOWER.] 



PEEWIT. [CHARADRIADJE.] 



PE'GANUM, from THiyavov, the Greek name of Rue, of which three 

 kinds are described by Dioscorides the Garden, the Mountain, and 

 the Wild. The last is said to be called Moly in Cappadocia and 

 Galatia, and by some Harmala. It is remarkable that even in the 

 present day a plant is found in the north of India, the Punjab, and 

 Cabul, which is called Hoormul by the natives of the above coun- 

 tries, and sometimes distinguished in India by the name of Lahoovee- 

 Hoormul, indicating that it was introduced from the direction of 

 Lahore. The Persian works on Materia Medica in use in India give 

 Holee as its Greek name, according to Dr. Royle (' Illustr.,' p. 155). 

 It is interesting to find that the plant to which these names are 

 assigned by the natives of the country is the Peganum Harmala of 

 botanists, a fact which shows that the investigations of the West had 

 arrived at the same conclusion as those in the East respecting the 

 plant alluded to by Grecian authors ; and this enables us to put more 

 faith in the results of such investigations than is sometimes done. 

 The plant, which is called Syrian Rue in gardens, belongs to the 

 natural family of Rutarerr, and is of easy culture in any light soil. 

 The seeds, which were formerly in use in medicine in Europe, still are 

 so in the East, but are not possessed of any peculiar or very active 

 properties'. 



I'K'KKA, a genus of Plants inhabiting Guyana, and furnishing the 

 ri or Sawarra Nuts of the shops, a very different fruit from that 



> which the name of Saouari is given in Guyana. Pekea comprehends 



pro species, the P. butyrota and P. tuberculoia: the former is unknown 



in this country ; the latter, which yields the fruit in question, is a 

 very large tree inhabiting the woods of Guyana, where it is called Tata- 

 youba by the Garipou Indians. It has opposite digitate leave?, whoso 

 leaflets are oval, smooth on the upper side, but white with down 

 beneath ; the terminal leaflet is said to be 8 inches long by SJ inches 

 in breadth, while those at the sides are much smaller. The flowers 

 are unknown. The fruit consists of greenish compressed drupes, 

 which adhere around a common centre, and contain a single seed of 

 large size, covered with a brownish rugged woody shell, and containing 

 a kernel of a soft consistence, and of the most delicate buttery quality. 

 It is by far the best of the South American nuts that are brought to 

 England, and much superior to our own walnuts, almonds, and filberts ; 

 but it is scarce and dear in most seasons. 



PfJtfa titberculosa, 



PEKTOLITE, a Mineral occurring in spheroidal masses which have 

 a radiating fibrous structure. Its colour is grayish. Hardness 4-0 to 

 5-0. Lustre pearly. It is nearly opaque. SpeciBc gravity 2'69. It is 

 found in large masses on Monte Baldo in the Southern Tyrol, and at 

 Monzoni in the Fassa-thaL Its analysis by Von Kobell afforded 



Silica 51-30 



Lime .. 33*77 



Soda 8-26 



Potash 1'57 



Alumina and Oxide of Iron .... 0'90 



Water 3-89 



99-69 



PELAGIA. [MII.LEPOHID.E ; PCLMOGRADA.] 

 PE'LAGUS, De Montfort, a genus of Ammonites. 

 PE'LAMYS. [HYDRIDE] 



PELARGO'NIUM is the name given by botanists to the gaily 

 painted flowers which are usually called Geraniums in our greenhouse 

 The latter differ obviously from Pelargonium in having regular flowers, 

 and in being herbaceous plants, while the genus in question consists 

 almost entirely of shrubs with flowers as irregular as those of the 

 Pansy. There is a large number of genuine species of this genus, 

 chiefly inhabiting the Cape of Geod Hope ; and as these intermix very 

 readily, producing in groat abundance shrubs which are capable of 

 being perpetuated by cuttings, a prodigious number of spurious species, 

 as well as acknowledged varieties, have found their way into the 

 writings of systematic botanists. For example, De Candolle enume- 

 rates 369 supposed species, of which at least one-half are of artificial 

 origin. While however science has been embarrassed by this facility 

 of cross-breeding, the gardens havo been enriched by crowds of the 

 most beautiful objects, in which the features of their savage progenitors 



