CHOCOLATE NUT-CHONDROPTERYGII. 



of the chalk, although they are now very rarely found 

 in the quarries in that neighbourhood. 



CHOCOLATE NUT is the Ttieobroma cacao o! 

 Linnaeus. See THEOBUOMA. 



CHOLEVA (Latreille). A genus of coleopterous 

 insects, belonging to the section Pcjitamcra, and 

 family Silphidtc. This genus, together with those of C'a- 

 tops, Ptomaphagus and Myl&chus, form a small group, 

 distinguished by their small size, and great agility ; 

 the antennae with the club five-jointed, the eighth joint 

 being very minute, and the elytra rounded at the tips. 

 Mr. Spence has published a monograph upon the 

 group in the Linncean Transactions. The insects 

 are of dark and obscure colours, frequenting dry 

 bones, putrid fungi, and vegetable matter in a state 

 of decay. There are numerous British species. 



CHOMELIA (Jacquin). West Indian shrubs, 

 formerly culled Lrora by Lambert and Swartz. Lin- 

 naean class and order, Tctrandria Mbnogynia ; natural 

 order, Rubiacea;. Generic character : calyx tubular, 

 limb four-cleft, recurved ; corolla tube long, cylindri- 

 cal, limb in four divisions, spreading points of the 

 divisions acute ; stamens with short filaments inserted 

 in the tube ; anthers linear, and somewhat prominent ; 

 style filiform ; stigma in two spreading processes ; 

 drupe oval, containing a four-furrowed two-celled 

 nut, each cell one-seeded. This genus being nearly 

 allied to the ixoras, also partakes of their ornamental 

 character. 



CHORAGUS (Kirby). A minute genius of 

 British coleopterous insects, of whose family ento- 

 mologists are at variance. It is of an ovate form, 

 with the head deflexed, the antennas long and termi- 

 nated by a club ; the legs are short and of a moderate 

 thickness, nevertheless the insect possesses the power 

 of leaping in a remarkable degree. Mr. Kirby, by 

 whom it was first described, thought it allied both 

 to Cri/ptocephalus (from the length of the antennae 

 and form of the body), and Cis (from the former being 

 clubbed). Mr. Stephens places it amongst the 

 PlinidcE, whilst M. Robert has recently figured it as 

 an Aiithribus, a genus allied to the Bruchidce. It is 

 found amongst grass and low herbage, but is very 

 rare. 



CHORIZEMA (Labillardiere). A genus of 

 beautiful shrubs, natives of New' Holland. Linnaean 

 class and order, Dccandria Monogi/nin ; natural order, 

 Leguminoscc. Generic character : calyx two-lipped, 

 upper one cleft, lower one trifid ; corolla keel belly- 

 ing, wings short, style short ; pod swollen, many- 

 seeded, nearly sitting. These are extremely neat 

 greenhouse plants. The C. Henchmannii deserves a 

 place in every collection. They are propagated by 

 cuttings. 



CHRISTMAS ROSE is the Hellebonu niger of 

 Linnaeus. One of a herbaceous family of plants in- 

 digenous to Europe, and long introduced into gardens 

 on account of their early flowering. The whole of 

 the hellebores are said to contain poisonous principles 

 in a greater or less degree, though some of them are 

 very fragrant. The flowers generally appear before 

 the* leaves, and are some of the first gems of the 

 spring. They are propagated either by dividing the 

 root or by seeds. 



CHRIST'S THORN is the Zyziphiu spina Christi 

 of Willdenow. It is a native of Egypt, and is culti- 

 vated in our greenhouses, and easily increased by 

 cuttings. 



CHROMIS. A genus of spinous-finned fishes 



belonging to the family Labroidrs. Their general 

 characters are : their lips and intermaxillary bone* 

 contracted ; a single dorsal fin with two produced 

 filaments, teeth set like those of a card on the jaw 

 bones and the palate, their lateral ones intercepted, 

 the ventral fins produced in long threads. There are 

 numerous species, several of which are occasionally 

 found in the British seas. They are not of large size, 

 but they are esteemed as food. For some detail of 

 them, the reader is referred to the article LABROIDES. 

 CHONDROPTERYGII (CARTILAGINOUS FISH- 

 ES), An order or rather sub-class of fishes which differ 

 so very much in many of their essential characters 

 from the rest of the finny tribes, that naturalists have 

 sometimes described them under the name of reptiles 

 rather than fishes. But still, how much soever they 

 may differ from the other inhabitants of the waters, 

 they are decidedly fishes, only it is not easy to trace 

 a gradation either from them to the others, or from 

 the others to them. In some parts of their organisa- 

 tion they are no doubt inferior to the bony fishos, but 

 there are some others in which they are decidedly 

 superior. 



They differ greatly in the several divisions of the 

 sub-class ; but they all possess that general cartilagi- 

 nous texture of the bones, on account of which the 

 name has been given them. This character varies 

 much however in the different genera, so that it is 

 not possible to frame a general description, so that it 

 shall be strictly applicable to any one species. In 

 general, we may say that they have some resemblance 

 to that division of the soft-firmed fishes, to which 

 Cuvier very accurately applies the name cf p/eclog- 

 nathes or " soldered jaws" because these fishes have 

 the bones of the mouth united to each other, and 

 consequently comparatively little motion of that 

 organ. There is another approximation in that 

 family to the sub-class now under consideration, 

 namely, a tendency to produce upon the skin, not 

 scales as in the other bony fishes, but grains or 

 tubercles of osseous matter. 



The chondropterygii have all the bones, forming 

 the cranium or cavity containing the brain, united 

 into a single piece, but still there are markings which 

 indicate portions resembling those that are united by 

 sutures in other fishes, though in some these mark- 

 ings are almost entirely obliterated, and the whole 

 skull consists of one case of flexible bone. The 

 vertebral column may be said generally to consist of 

 one single flexible piece, though in this also there 

 are differences, some having articulations marked 

 throughout its length, and even tolerably distinct 

 apart, while in others, as in some of the cyclostoma, 

 "round mouths," or suckers, there is scarcely any 

 indication of a joint even by a simple marking ; so 

 that these may be regarded as, in their skeleton at 

 least, being at the very bottom of the scale of verte- 

 brated animals, and connecting them with some of 

 the most simply formed tribes in the whole animal 

 kingdom, the myxine or hag being as much like a 

 slug or leech as a fish, although it has still the gene- 

 ral character and economy of a vertebrated animal. 



But it is in the general texture of the bone, rather 

 than its form, that the distinguishing character of 

 these fishes consists. In all other vertebrated animals 

 the bones are made up of plates, and these plates of 

 fibres, which extend in the direction of the length of 

 the bone, so that the bone is much more easily split 

 in length than broken across, whereas in the chon- 



