CRASSINA CRAT/EGUS. 



cardinal teeth, divergent, separated by a deep cavity; 

 two muscular impressions round, distant, united by 

 the marginal ligula, without any trace of posterior 

 sinuosity ; the impression of the retractor muscle dis- 

 tinct. There are eleven species described, all from the 

 Australian seas, and it is somewhat remarkable that 

 many fossil species are found in France, and no where 

 else. 



CRASSINA (Lamarck; ASTARTE, Sowerby). In 

 appearance this shell resembles a small crassatella, 

 being thick and solid, the valves closing in every part, 

 but it is distinguished from it by the position of the 

 ligament. It cannot either be mistaken for a species 

 of venus, since, on a comparison, it is found to pos- 

 sess not more than two teeth on each valve, and even 

 appears to have but one, very large, on the left valve, 

 the other projecting but slightly. The shell is or- 

 bicular, transverse, equivalve, sub-inequilateral, and 

 closed. Hinge with two divergent teeth, and two on 

 the other very unequal. Ligament external, and 

 placed on the longest side. The name of this genus 

 has been properly changed by Sowerby, several spe- 

 cies of this mollusc having been described under that 

 name, previously to Lamarck's adopting that of cras- 

 sina, a circumstance he either overlooked or was ig- 

 norant of. The Venus Danmoniensis of Montague 

 illustrates this genus. 



CRASSULA (Linnaeus). An extensive genus of 

 greenhouse succulents, natives of the Cape of Good 

 Hope, Linnsean class and order, Pentandria Penta- 

 gynia ; and natural order, Crassulacece, Generic 

 character : calyx tubular, and five-parted ; petals 

 connected at the base, and bearing the stamens ; 

 five nectariferous scales below the germen ; seed- 

 vessel five-pointed, bursting inwardly, many-seeded. 

 The crassulas are mostly what are called under, or 

 half shrubby plants, with thick fleshy leaves, and 

 many of them bear showy flowers. Like all other 

 succulents, they thrive best in a dry soil, mixed with 

 lime rubbish, to allow of water draining quickly away 

 from the roots. Cuttings strike readily, if allowed 

 to dry for a day or two after they be cut, that the 

 fresh wound may be somewhat dried before placing 

 in the soil. 



CRASSULACE^E the house-leek family. A 

 natural order of dicotyledonous or exogenous plants, 

 containing nineteen known genera, and nearly three 

 hundred species. In its succulent stem and leaves 

 this order resembles Cactca: and Portulacece. It bears 

 an affinity to SaxifragecE and Illecebrece, but differs 

 from these orders in its hypogynous scales. There 

 is no instance of a double flower in the order. 



Its essential characters are : sepals from three to 

 twenty, more or less united at the base ; petals equal 

 to them in number and alternate with them, inserted 

 into the bottom of the calyx ; stamens inserted with 

 the petals, either equal to them in number and alter- 

 nate with them, or twice as many, those opposite the 

 petals being shortest ; filaments distinct, awl-shaped ; 

 anthers of two cells bursting longitudinally ; a hypo- 

 gynous nectariferous scale at the base of each ovary ; 

 ovaries of the same number as the petals, opposite to 

 them, placed in a circle, distinct, one-celled, tapering 

 into stigmas ; several one-celled carpels opening lon- 

 gitudinally and internally ; seeds attached to the 

 margin of the suture, varying in number ; albumen 

 thin, fleshy ; embryo straight ; radicle turned towards 

 the hi hi in. 



The plants belonging to this order are succulent 



herbs or shrubs with fleshy entire, or pinnatifid 

 leaves, and sessile cytnose flowers which are often 

 unilateral 



They are found most abundantly at the Cape of 

 Good Hope. They are also met with in Europe, 

 North and South America, Siberia, the East Indies, 

 and New Holland. None of the species inhabit the 

 West Indies. They grow on dry arid situations, 

 such as naked rocks, old walls, and sandy plains, where 

 there is scarcely any other kind of vegetation. They 

 imbibe nourishment by their whole surface, and do 

 not depend for it on the soil in which they grow. In 

 their properties they are refrigerant, and sometimes 

 acrid. 



The chief genera of the order are, Crassula, Sem- 

 pervivum, Sedum, Cotyledon, Umbilicus, Ttilcea, Globrir 

 lea, Rochea, and Rhodiola. 



Of the genus Crassida there are several species, 

 some of which are cultivated in our greenhouses on 

 account of their beauty. 



The genus Sempervivum (live for ever) derives its 

 name from the tenacity of life which is exhibited by 

 its species. Sempervivum tectorum, common house- 

 leek, is frequent on the tops of cottages in this coun- 

 try, and is often regarded by the country people with 

 feelings of veneration. Its leaves are cooling and 

 astringent, and when mixed with lard or oil are 

 applied to burns, and wounds. They contain malic 

 acid combined with lime. The fishermen of Madeira 

 rub their nets with the Sempervivum glutinosum in 

 order to render them hard and durable. 



Sedum telephium, orpine, or live-long, is common 

 on borders of fields and near hedges in Britain. It 

 was formerly considered valuable as a vulnerary. 



Sedum acre, biting stone-crop, or wall-pepper, is a 

 common British plant. All parts of it are acrid and 

 pungent. The expressed juice is emetic and purga- 

 tive, even in small doses. The plant has been used 

 as an antiscorbutic. In Germany it is applied to 

 swellings of the joints, sometimes with considerable 

 benefit. It is a plant which botanists find great diffi- 

 culty in drying. It will continue to vegetate under 

 great pressure applied at a high temperature. Its 

 vitality must be destroyed by being dipped in boiling 

 water before any attempt is made at exsiccation. 

 The young shoots of Sedum album are boiled and 

 used for food in some parts of France. Sedum 

 rupestre and reflexwn are cultivated in some parts of 

 Holland and Germany for the purpose of being mixed 

 with lettuce as a salad. The leaves of the Umbilicus 

 pendulinus, wall pennywort, are applied externally 

 as a cooling remedy. Rhodiola rosea, rose root, is so 

 called in consequence of its large root, when dry, 

 yielding a smell similar to that of roses. It is com- 

 mon on wet rocks in different parts of Britain, par- 

 ticularly on the Scottish mountains. It is sometimes 

 cultivated in gardens, and is the badge of the clan 

 Gunn. 



CRAT^EGUS (Linnsus) is the generic name of 

 the well known hawthorn. It belongs to the twelfth 

 class Icosandria, and to the natural order Rosaceat. 

 The species are mostly natives of the colder parts of 

 America and Europe. The common hawthorn is one 

 of our most beautiful wild shrubs, and universally used 

 as a hedge plant, making an excellent fence, it being 

 self-defended by its thorns, as well as by its stubborn 

 and hardy constitution. There are six ornamental 

 varieties of the common hawthorn, one or two of 

 which bear red or crimson flowers, and which when 



