11BI 



VEGETABLE MORPHOLOGY. 



VKXKUID.E. 



llfll 



20. The Kegion of Palms and Mtlatl<M*acr, or Brazilian kingdom, 

 including Brazil, or South America, on the east of the Andes, between 

 the equator, aud the tropic of Caprioorn ; teniperature 59 to 837. 

 Thi region is remarkable for the Dumber of its genera and specie*, 

 the size of individual trees, the dense forest*, and the numerous climb- 

 ing and parasitical plant*. Vegetation seems here to attain its greatest 

 activity and energy. The orders which abound most are I'almaceir, 

 Jlctmadoracett, tietneriactat, ittlattomaeea, l*apindacea, and, altogether 

 confined to this region, Vockyaceue. The cultivation is very similar to 

 that of Mexico. 



21. The Kegion of Woody Comporitd. In South America, on the 

 cast of the Amies from the tropic of Capricorn to 40 S. lat. : tempera- 

 ture 59 to 7475*. There are but few tropical plants in this region, 

 and extra tropical plants, especially European forms, arc abundant, 

 more than half being common to this region and Europe. The Woody 

 Compotitir abound. This region consists chiefly of plains (pampas), 

 which for hundreds of miles present almost the same vegetation, con- 

 sisting chiefly of Thistles and Grasses. Wheat, the Vine, and the 

 Peach, are cultivated. 



22. The Antarctic Kegion includes the south-westerly part of Pata- 

 gonia, Tierra del Fnego, between 50 and 55 S. lat. : temperature 41 

 to 47'5 '. In this region there are no tropical plants, and its vegeta- 

 tion resembles in a great measure the North-European flora (region 

 2). In some of the genera there is an approach to the South African 

 and Australian flora. 



23. The Region of SUpeliaa and Meaembryanthemums. This em- 

 braces South Africa from the tropic to 35 S. lat : temperature 54-5 

 to 72 5. The vegetation of this region is not luxuriant, but it is very 

 rich in forms. There are no dense forests nor climbers, but many 

 succulent plant*. The orders Jtetliacctr, Iridacett, Proteacea, Ericacea, 

 Picoidaceee, Bruniacea, JJiotmacea, (reraniaccie, Oxalidacece, and Poly- 

 ffolacete, embrace its characteristic vegetation. On the randy coasts 

 the genera Slapelia, iletembryan'hemttm, and IHotma, are found, aud 

 on the mountains I'rutra, Erica, and Crauula. The cultivated plants 

 re those of Europe, with the Miua Paraditlaca, Convolvulus Batata*, 

 the Tamarind, and f<oryh*m Ca/romm. 



24. The Kegion of Eucalypti and Epacridacta. It includes extra- 

 tropical Australia and Van Diemen's Land : temperature 52*25 to 

 "U'5 J . Vegetation is not abundant in this region ; but this deficiency 

 is compensated by the variety and peculiarity of its forms. The most 

 abundant of the trees are the Eucalypti, which form three-fourths of 

 all the woods. Next come the genera of J'roteacaf. Banktia, //air a. 

 Dryandra, Oreviltaa, IK. : and next to these follow Epacridacett, Dial- 

 motor, and Catuaracca. Its cultivated plants are all European. 



25. The Kegiou of New Zealand includes the two New Zealand ides : 

 temperate. One-half of the species are European. The vegetation is 

 not characterised by the prevalence of large groups. Some of the 

 genera approximate the South African flora, and some the Australian. 



(The following works should be consulted on the geography of 

 plants : Linnaus, Stalionet Plantarum ; Humboldt aud Bonpland, 

 Knai *wr la Gtographie da I'lantct ; Huinboldt, f>c Dittributionc 

 (jeograpktca Planturum ; Brown, General Remarks on the Botany of 

 Terra Amtralit; Scbouw, UruntLuyc einer Allyemcinen Pjlanzen- 

 (troy rapine ; Meyen, Grundria der Pflamen-Qcoyraiihie ; Bischoff, 

 Lekrbtick der Bot anile ; Hooker, in Hurray's Dictionary of <leo- 

 yrapky; De Candollc, art. Qfographie del Plantei Diet, da Science* 

 .\alurtllti ; Lindley, Int. But., 2nd. oil. ; Meyen, Geography of Planti, 

 translated for Kay Society by Mis* Johnston; Balfour, Clou-Book 

 of Botany ; Johnston, PHytical Allot.) 



VKUKTABLE MOKPHOLOQY. lMKTAMOBnjosi.] 



VEINS, a part of the vascuUr system of the higher animals. The 

 rrius return the blood which has been brought by the arteries into the 

 capillaries to the right side of the heart. [ARTERIES; CAI ILLAIUES.' 

 The veins, like the arteries, are clastic tubes, which ramify throughout 

 the body. They are generally placed more superficially than the 

 arteries, but some of them are deep-seated. They anastomose more 

 frequently than the arteries. 



The veins have much thinner coats than the arteries, and collapse 

 when cut across or emptied. In most veins of tolerable size three 

 coats may be seen, which have been named External, Middle, and 

 Internal. The External Coat is strong and tough, but thin, and is 

 composed of fibres of the same nature as those of areolar tissue. The 

 Internal Coat is very like that of arteries. It consists of a membrane 

 of fine elastic fibres, which are covered over with a layer of epithelial 

 cells. Between these two coats is a layer of fibres, which in some 

 places is more dintinct than at others, and is then called a Middle Coat. 

 The coats of the veins are supplied with nutrient arteries, the so- 

 called Vssa Vasonim. 



The veins are provided with valves, by means of which the blood is 

 prevented from returning in the direction in which it is moving. The 

 valves are formed of semilunar folds of the lining membrane, which 

 are strengthened by the deposit of fibres of white and yellow areolar 

 tissue. These flaps, or folds, arc usually placed opposite each other, 

 and are so placed as to offer no obstruction to the onward flow of the 

 blood, but when from pressure or any other cause it is driven back- 

 wards, the reflex current will press t h- valves inwards until their edges 

 Met in the middle and block the channel entirely up. In mnny veins 

 hese valves an absent, nor are they observed iu the veins of reptiles 



and fishes ; and there are but few in those of birds. It was the cir- 

 cumstance however of the occurrence of these valves that arrested the 

 attention of Harvey, and led him to pursue the course of the blood 

 from one side of the heart to the other. ( HFAIIT.] 



V F.I \s. M1XEU.VL. (MiNKHAL VMS*.] 



VKLELLA. [AcALKru*.] 



VELIA. [HYDHOUKTRID*.] 



VELLA (Latinised from Velcor, the Celtic name of the Cress), a 

 genus of plants belonging to the natural order Crueijrnr. It has an 

 ovate pouch, with a dilated winged leafy flat style, longer than the 

 convex valves. The flowers are yellow, and are, as well as the pod, 

 erect. 



I', anntta was found in the time of Hay on Salisbury Plain, but has 

 not since been noticed. It has doubly pinnatifid leaves and deflexed 

 pouches. 



V. pxudocytitut, False Cytisus, or Cress-Rocket, is a native of Spain ; 

 it has yellow petals with long dark-purple claws ; the larger stamens 

 are connate by pairs ; the seeds two iu each cell. 



VELUTI'NA, Lamarck's name for a genus of his family Macrotto- 

 mala, from the rest of which however Vtlutina remarkably differ?. 

 The shell is subglobose ; spire short, composed of two rapidly en- 

 larged ventricose whorls; aperture large, subovate; peritreme thin, 

 entire, separated from the last whorl; columella twisted and thin; 

 epidermis velvety. 



Dr. J. E. Gray places the Vclutinida, with the stogie genus Vclutina, 

 between the Truncatellida and the Paludinidtt. 



Ex. Vclutina litriyata. 



Velulina Ittciynta. 



VENERICA'RDIA. 



VENE'RID.t;, a family of Conchiferous Molliura. 



The genus Venus of Linnaeus was arranged by him in the i 

 section (Bivalvia: Concha) of his Teitacea HfoUutcaSimplicia, oblKta 

 Tetla Calcarea, between Donax and Spondylut. 



He divided the genus into the following sections : 



* Pubcnlet. 

 Species : Dione, Paphia, marlca, dytera. 



" Impubcra Subcordat<e. 



Species : Venus terrucota, caiina, canceltata, gallina, pclulca, 

 Jlexiuaa, crycina, mercenaria, Mandica, cltionc, macnlala, K> 

 lata, cattrentii, Phryne, Meroe, dfjtorata, fimbriata, rcticulata, ijuamo$a. 



*" Impubcrci Orbicvlattt. 



Species:!', tigerina, prottrata, Pennsylranica, incnutata, punctata, 

 c.coleta, borcalit, jiectinata, icripta, edentula. 



"" Impuberet Ovala, supra rimam subangulatax 



Species : V. literata, rotundata, decuuata, and nV. 



Such is the arrangement of Linn;vus iu his list edition of tho 

 'Systema Natunc,' and he characterises the hinge of the genus as 

 consisting of three teeth, all approximate, the lateral teeth diverging 

 at the apex. 



The Cardiacea of Cuvier consist of the genera L'artlium (with the 

 sub-genus JJcmicardium), Donax, Cyclat (with the sub-genera ( ' 

 < 'v/.i -iiia, and Oalathea). Varbu, Tcllina, Loripet, Lucina, I'liyulina, 

 Ventu, Corbula, aud Mactra (includiug the true Mactrtt and the 

 Lavignons). 



The genus Venut he divides into the true \\ncrct, Attartc or 

 Crauina, Oytherca, Capia, aud Petricola ; and he defines this great 

 genus Vcniu as comprising a multitude of shells whose common cha- 

 racter is to have the teeth and lamina: of the hinge approximated under 

 the iimbo in a single group. They are, he remarks, in general more 

 flattened aud more elongated parallelly to the hinge than the Cardm. 

 Their ribs, when they have any, are nearly always parallel to the 

 borders, which is the opposite of the Cardia. The ligament often 

 leaves behind the umbones an elliptical impression named by modern 

 zoologists the Corslet ; and there is nearly always iu front of the 

 umbones an oval impression designated a< the Lunule. 



The animal has always two tubes susceptible of more or It- 

 jection, but sometimes united to each other, and a compressed foot 

 which serves for creeping. 



Dr. J. K. Gray places the Vmerida as the first family of his order 

 Pkyllopoda, with the following genera: Arlcmil, Cythcrea, Merot, 

 (jralclupia. Trigona, Chiont, Circe, Duiina, Alcrccnaria, Anomalocardia, 

 Vypreria, Ventu, Tapa, Venerupii, and dementia. 



The Vcneridit are immediately followed iu Dr. Gray's arrangement 

 by the Cyrtnidrr, which comprise the following genera : ( 

 Moina, Vdorila. Cyclat, and Puidium. 



The Card\ada immediately follow. Woodward, in his 'Xsnosl,' 

 places the Vcnerida between the Cyprinida and Maetridtr, and include* 



