71J 



< Al.ATHinH'M. 



CAI.CAKKODS SI'AII. 



710 



front bidentated ; colour, that of flesh sprinkled with spot* of carmine 



' . i n -'.'- .-- :. -. 8 I I !' g !. 



CALATHI I'll M.. i modern name for the flower-head of the plant* 

 celled Compotilir, the common Calyx of Linnieus. It oounU of a 

 flattiah or conical cellular dink, called the Receptacle, upon which a 

 number of HI nail flower* are very compactly arranged ; and its surface 

 is either naked and even, except no far aa the scam left by the attach- 

 ment of the flower* render it otherwise, or covered with hairs, 

 bristles, or scales, named Palen. IU margin is uniformly furnished 

 with one or more rows of small leaves or scales which inclose the 

 flowers as within a cup. The form, number, texture, and proportions 

 of these scales often afford good generic characters. In reality, 11 

 Calathidium ix a short spike of inflorescence, the receptacle being the 

 depressed axis, its palerc bracts, and the external scales being other 

 bract* in a more perfect state. The Daisy, the Dandelion, and the 

 Sunflower, offer illustrations of this form of inflorescence. 



. A THUS, a genus of Coleopterous Insects belonging to the 

 section Gtodephaga and family Ilarpaiid<r. It has the following 

 characters : Body elongate, somewhat ovate, slightly point, 

 teriorly ; thorax wider behind than before ; anterior tarsi with the 

 three basal joints dilated in the males ; claws dentate beneath ; ]>alpi 

 with the terminal joint almost cylindrical, and truncated; labrurn 

 transverse, and slightly emarginated anteriorly. 



Upwards of twenty species of this genus have been discovered, 

 almost all of which are European. Their general colouring is black 



or brown ; one or two metallic- 

 coloured species however are 

 known. In England eight species 

 have been enumerated, most of 

 which are common. Four species 

 may be found under atom 

 rubbish in the neighbourhood of 

 London ; of these C. citteloidet is 

 exceedingly common, frequently 

 being met with in pathways, Ac. ; 

 it is about half an inch long, and 

 of a black colour; the air 

 are pitchy black, with the basal 

 joint red ; the legs are black, ami 

 in some specimens red. The 

 wood-cut here given of C. latut 

 wi'l enable the reader to form an 

 Mea of their general appearance ; 

 it is a very rare species in this 

 :-y, and differs chiefly from the one above mentioned in its greater 

 width, and the thorax having the lateral margins of a reddish hue. 

 I'AI.r.VIKK GBOSSIER, the coarse calcareous building-stone of 

 which, geologically speaking, is coeval with the blue clay of the 

 of London, and contains many identical sheila. These con- 

 stitute the types of the Eocene Tertiary series of Mr. Lyell. 



CA'LCAR, a genus of Coleopterous Insects belonging to the section 

 ffcteromera and family Tenebrioni<l<r. This genus is distinguished 

 from the allied genera (//.'//>y,A/<rK*, Apis, &c.) by baring the body 

 linear, the head emarginated anteriorly, and the thrte or four terminal 

 joints of the antenna) nearly globular; the thorax is longer than 

 broad, truncated anteriorly and posteriorly, and of nearly equal width 

 throughout. 



CALCAR, or Spur, in flowers, is a hollow projection from the base 

 of a petal, and has usually a conical figure. It was called Nectary by 

 Linnams, but it rarely secretes honey. Its use is unknown. The 

 spurs of some of the Orchidacea are several inches long, and many 

 times longer than the flowers to which they belong, hanging down 

 like vegetaU tails. 



CAI.CAKKors .SPAR Under this term it is usual to include 

 only those varieties of Carbonate of Lime which occur in distinct 

 individual crystals of the rhombohedral system, the name never being 

 tued to denote Arragonite, or any crystals of carbonate of lime 

 belonging to the prismatic system ; nor U it usual to apply it to those 

 more or leu crystalline limestones of which marble is the purest 

 variety, where each crystal is so embedded in the mass as to have 

 lost all Individuality. In a word, these rocks are of such importance 

 ;.iid interest that they do not admit of our treating them as a mini ra- 

 logical variety, but as masses formed by the aggregation of numerous 

 crystals of it These are noticed therefore under the heads Liu i 

 and MAIIULE, while we shall here confine ourselves to the individual 

 crystals of which the others are composed. 



This substance present* us with one of the most interesting objects 

 which can engage the attention of the mineralogist, not only <>n 

 account of the important port it plays in the geological structure of 

 the earth, being frequently almost the sole ingredient of beds of rock 

 of great thickness and extent, produced at every geological epoch, hut 

 al o from the beauty and diversity of its crystalline forms, and from 

 the peculiarity of several of iU physical properties. The stud)' 

 and a correct knowledge of this mineral species have also become 

 of Btill greater importance since the discovery of the principles of 

 isomorphism, by which it is shown that it is the most perfectly 

 developed individual of a very large class of the mineral salts of 

 carbonic acid, of which it may consequently bo considered the type. 



If any crystal of calcipar, whatever its form, bo carefully exainin.-,!, 

 an appearance indicating a tendency in it- substance to break or split 

 in the direction of three planes symmetrically r< 1 ' ! to the form 

 may be peroelve.l, and by a g.-ntl.- . holt- is rvadily r> 



to fragments, each of which may with a little care be brought 

 form of the rhombohodron rcpresci 'lie faces of which 



are parallel to the three planes of cleavage above mentioned. Tin-, 

 in the language of Haiiy, in the primitiv.- form of calc-|>.-ir, ami 

 represents, according to his theory, the shape of the ultim.ct.- mole- 

 cules or atoms of carbonate of lime, by the aggregation of which, 

 according to certain laws, its various crystals are produced. Alt 

 this rhombohedron occurs rarely or never as an unlnol. n crystal of 

 pure carbonate of lime, it in nevertheless th.- most convenient p 

 form, to the axis of whirh the faces of all other erytals of this 

 substance may be referred, and it is therefore select, 

 purpose. These forms, although far exceeding in iminWr those 

 observed in any other mineral species, are however (omitting the 



Fig. 1. 



Fig. S. 



Fig. 5. 



regular hexagonal prism, c, and its terminal f.-iccs, o, ify. i;) l,nt of 

 two kinds, being cither rhi>m)ihedrniis, of which \ i-']>rc 



nented in fi'ji. 1, 2, 3, and 4, or Kcaliimln-drons. one of th,- i n ->-t 

 common of whicii is seen in fg 5. Tin i ; . ,-ach other and 



their coml.inations have lipcn developed principally by I 

 Bournou, and Monteiro, by whom no less than 3d different rlmm- 



