CHALCOLITE. 



CHALK I'OKMATION. 



M i 



antenna under the body, and it appeared that thin organ was used 

 in making the spring. If this should be the cam, it would be a 

 molt extraordinary n*e to make of thaw part*, which are usually con- 

 sidered either M organ* of hearing or touch. We may obeerre that 

 the Bpeciea which we found to possess this power in a high degree 

 had immensely thick antenmp, and the hind leg*, the usual leaping 

 organ*, do not appear at all adapted fur that purpose, nor can we 

 discover any other part that is. Although in C. daripa (the species 

 figured) thti hinder femuro are thick, yet it does Dot possess the power 

 of leaping; and when we examine the structure of this part, we find 

 that it differs much froui the thickened thigh of leaping insects. It 

 i* formed upon the same type as the same part in some of the Donacia 

 tribe (among beetles), which appears to be used for clinging ; and this 

 species, inhabiting marshy situations, would probably require such a 

 clinging apparatus for the same reason as the Donacia do, namely, to 

 keep them from falling into the water. A figure of the leg of a 

 species of Donative is given, to show the resemblance both in the 

 femur and curved tibia. 



The Chalcididit are all parasitical in their larra state. Some 

 are so minute as to undergo their metamorphosis in the eggs of other 

 insects. The chrysalides of some of the lepidopterous insects not 

 unfrequently form the nidus of an immense number of these little 

 insects. One species of Chalet* generally confines its attacks to the 

 chrysalis of one species of lepidopterous insects ; but occasionally we 

 have reared more than one species of the Chalciduke from the same 

 chrysalis. 



Mr. Walker, a gentleman who has written much on this group of 

 insects, looks upon it as a great section of Hymenopttra rather than 

 a family, and his views appear to us correct. The Chnlcididtc ore 

 divided by him into two sections, which he calls Chalcide* Pentameri 

 and Ckalcida Tetrameri, names applied from their having five or four- 

 jointed tarsi ; each of these sections is again subdivided into several 

 families, the species of which are exceedingly numerous. Mr. West- 

 wood, who, as well as Mr. Walker, has paid great attention to this inter- 

 esting group, states that there are probably 1500 species in England. 



CHALCOLITE, a mineral of a green colour containing Uranium. 

 [URANIUM.] 



CHALI'COMYS, a genus of Rodent Mammalia, allied to the beaver. 

 From EppeUheim ; in Tertiary beds. 



CHALICOTHE'RIUM, a genus of Fossil Pachydermatous Animals 

 allied to the Tapirs, comprising two species found at Epplesheim, 

 about 12 leagues south of Mayence, in sand, supposed to be of the 

 Second Tertiary or Miocene period of Lyell. (Kaup, Description 

 <TOaewunt Fomila, Darmst, 1832.) 



CHALILITE, a mineral belonging to the group of Zeolites. It 

 occurs massive. It* fracture is splintery and flat conchoklal. Hard- 

 ness 4'5. Colour deep reddish-brown. Lustre between vitreous and 

 resinous. Translucent on the edges. Specific gravity 2'25'2. 



By the blowpipe it becomes white, and spreads out ; with carbonate 

 of soda it effervesces, and fuses with some difficulty into a white bead 

 with a pearly lustre ; with borax it fuses into a colourless gloss. 

 It is found in the county of Antrim, Ireland. 



Analysis by Dr. Thompson : 



Silica 36-56 



Alumina 26-20 



Lime 10'28 



Peroxide of Iron 9'28 



Soda 272 



Water 16-66 



101-70 



CHALIMUS, a genus of Entomostracous Criulacea allied to Caliyut. 

 [CALI<;I-H.] 



CHALK FORMATION and CRETACEOUS GROUP, in Geology, 

 consist of the upper strata of the Secondary series immediately 

 below the Tertiary, series and superincumbent on the Wealden, or 

 where that is wanting, on the Oolitic system. This group is common 

 rope, and also to at least a part of Asia. It consists of chalk 

 resting upon either an arenaceous or argillaceous deposit. The Chalk 

 bears a remarkably uniform mineralogical character over a surface 

 extending from the British Islands through Northern France, Northern 

 Germany, Denmark, and Sweden, into both Euro|>ean and Asiatic 

 Rumia. (De La Heche, ' Res. in Theor. GeoL') The Cretaceous system 

 is subdivided into the following strata : 

 , Upper. 1. MsMtrlcht brd 

 I Iwrr. J. Chalk with fli 

 I. Chalk vlihoui 



and Chalk with nurl 



! Upper Onensuul 

 Omult 

 Lower Onctuand. (tftaeomit*) . 



The area over which this system prevails in England, and the various 

 strata which it contains, have been well defined by geologists. 



The Cretaceous Group occupies nearly the whole of the south- 

 eastern part of England. A line drawn from C'rewkernc on the south- 

 west to Hunstanton on the north-east forms its western boundary ; 

 and it extends from this line to the east coast, with the exception ,,f 

 a small part on the south-east. It is also found on the north nf the 



. ... 



I Marlj. 



ril . . 



lints . . 

 ut flint-, , 

 .1.1. _ -i In 



which numerous upcclc* of 

 marine fotkiiU arc found. 



Wash forming the Wolds of Lincolnshire. It is intersected by the 

 Humber and constitutes also the Wolds of Yorkshire. It terminates 

 near Flamborough Head at Speeton, about six miles north of that 

 promontory. The same formation appears to prevail in the nortli nf 

 France, extending to the Cretaceous district of Aix-lo-Chapclle. The 

 Chalk, or upper portion of the system, is in some parts covered with 

 the strata of the Tertiary series ; in other ports it is <lnu<l< d. The 

 Greensand crops out round its edge, which is broken ami interrupted 

 in many places where the lower strata appear. 



On the north-east the Chalk appears in a narrower belt along the . !iir 

 from near Cromer to Hunstanton. From Cromer along the coast to the 

 mouth of the Thames, and along the north bank of that river.it 

 eealcd by the upper strata, which extend a considerable distance inlaml. 



Beginning with Norfolk and proceeding southwards, the boundary 

 line between the Chalk and the superior strata is about 4 miles east 

 of Snettisham, 2 miles west of Diss, 8 miles east of Mildenhall, 

 between 4 and 5 miles west of Bury St. Edmunds, continuing to the 

 north-east of Hertfordshire by Hertford and near St. Alban's, to 3 miles 

 south-east of Wendover. 



In the northern part of this district the Chalk has in a few places 

 been partially denuded. On the north-east there is a small piece of 

 Chalk along the banks of the Bure. The town of Norwich also 

 upon Chalk, which, in its vicinity, extends along the banks of the 

 Yare and Wensum. There is a piece of Chalk likewise at each side 

 of small parts of the Stour and of the Orwell. The strata super- 

 incumbent on the Chalk series extend a little beyond Uxbridge on the 

 west, and then run in a narrow tongue to the north-west, 3 miles 

 south of Wendover, which intervening space at that point is the 

 whole width of the denuded Chalk, Wendover being there its western 

 limit. The Chalk becomes wider towards the south-east, taking in 

 Maidenhead ; it ia again partially covered a little to the west of that 

 place, and continues in a very uneven line to Reading, Newbury, and 

 a little to the east of Marlborough. The Tertiary strata then nin 

 from west to east by Kingsclere, Basingstoke, Guildford, to 3 miles 

 north of Dorking, round by the Darent, and appear near Woolwieh 

 and Greenwich. Another detached portion appears in the north-west 

 of Kent, taking in the Isle of Sheppey, and continues from the (estuary 

 of the Medway along the coast to the Isle of Thanet The Chalk is 

 covered on the west and north of Canterbury and at Sandwich ; the 

 beds which cover it terminate on the coast at Deal. On the south 

 coast, from Worthing westward, the Chalk is again concealed by the 

 superincumbent series, extending nearly in a straight line through 

 Chichester as for as a little to the east of Salisbury ; it then continue* 

 in a south-west direction nearly as far as Dorchester. The Chalk 

 posses entirely across the Isle of Wight nearly from east to \v. 

 a narrow ridge consisting of vertical strata, from Culver Cliff to 

 Compton Bay ; there is also a small piece on the south of the island. 

 The limits of the Chalk on the other side, where it is bounded by the 

 outcropping of the lower strata of the system, remain to be noticed. 

 The cliffs of the whole of the Isle of Thanet ore composed of Chalk. 

 The chalk-cliff* again commence near Deal, and are continued post 

 Dover to East Weore Bay, a distance of about 13 miles. As the 

 Chalk rises from Dover towards Folkstone the upper beds disappear, 

 and the cliffs consist entirely of the lower members of that stratum. 

 The rise of the Marly Chalk occurs about 1J mile to the east of the 

 escarpment of Folkstonu Hill, which is 566 feet high. Just at the 

 rise of this bed there is a very copious and perennial spring called 

 Lydden Spout About 2000 paces west of this spring the cliff recedes 

 from the sea, and the intermediate shore thence to Copt Point in 

 occupied by a mass of ruins which has fallen from above. The sudden 

 transition from the chalk-cliffs is very remarkable. Turning inlart'1 

 the chalk-range is bounded on the south by the outcrop of the < 

 sand strata, which extend 4 miles north of Ashfonl, 3 miles north of 

 Maidstone, and is cut by the Medway, whence it forms a line eun ini; 

 outward to the south as far as the Darent, where it is 5 miles north 

 of Sevenoaks. Merstharn is on the boundary, which then continues 

 in nearly a west direction, immediately north of Reigate to Box Hill, 

 near Dorking, and thence to Guildford, leaving o very narrow ridge of 

 Chalk. From Guildford to a point about 2 miles from Karuham tin n> 

 is a remarkable ridge, called the Hog's Back, produced by on upthrow 

 of the Chalk and the breaking off of the southern portion of theem-ve. 

 The coast between Copt Point and Beachy Head, near those res| 

 points, is occupied on each side by the Greensand, and the inter- 

 mediate space by the Wealden Clay and Hastings Sand : the two 

 latter do not belong to this series, being lower denuded strata. The 

 Sussex chalk-range, or South Downs, commences at Eastbouni' 

 Beachy Head, and continues thence along the coast beyond Slim > ham 

 anil onwards in a west-by-north direction. The Greensand bounds it 

 on the north, and leaves a range of Chalk varying from 8 to M 

 in breadth. About 3 miles south-west of Petersficld the Greensand 

 again sinks below the Chalk, which is connected with the north range 

 by the Alton chalk-hills, running from near Farnham to near Butser 

 Hill (917 feet). 



It now remains to define the boundary of the Chalk from Dorsetshire 

 on the south-west to Norfolk on the north-east It has been thus 

 described by Dr. Fitton : " The great range of the chalk-esciu j 

 in the interior of England, which stretches like the shore of a sea or 

 lake from Crewkemein Dorsetshire to the north-east of Dunstoble in 



