cow 



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C R I 



CO'WRY. The common or familiar name 

 for shells belonging to the genus Cyprsea. 



CRAG. A tertiary deposit of the older 

 pliocene period, which has obtained this 

 name from a provincial term signifying 

 gravel. The crag is chiefly developed in 

 the eastern parts of Norfolk and Suffolk, 

 extending thence into Essex : it is seen 

 to rest on the chalk and on the London 

 clay, but generally on the chalk. By 

 some the crag has been divided into two 

 groups, the lower, or coralline, which is, 

 in some places, fifty feet or more in thick- 

 ness, and the upper, or red crag, thus 

 named from its ferruginous colour. . The 

 fossils of the crag are very numerous. 



CRA'NIA. (from cranium, Lat. a skull, 

 in consequence of a supposed resemblance 

 of the interior of the shells to a skull, 

 arising from some deep muscular impres- 

 sions.) A regular inequivalved bivalve ; 

 the upper valve very convex, patelliform, 

 with the umbo near the centre, the lower 

 valve flat, and nearly round, and pierced 

 internally with three unequal and oblique 

 holes. The arms of the animal are cili- 

 ated. Cuvier places crania in the class 

 Brachiopoda, division Mollusca. By La- 

 marck this genus is placed in the family 

 Rudistes, order Monomyaria ; and by De 

 Blainville in the order Palliobranchiata. 

 Cranise are found attached to stones and 

 shells, and are brought up, probably from 



freat depths, by cod-lines off the coast of 

 hetland, and with corals in the Mediter 

 ranean. Several species of fossil crania 

 are found in the chalk formation. 

 CRA/NIUM. The skull. 



CRASSATE'LLA. (from crassus, Lat.) A 

 genus of equivalved inequilateral close 

 bivalves. The hinge teeth two, with an 

 adjoining fossa ; the lateral teeth obso- 

 lete. The cartilage inserted in a pit 

 formed in the hinge. 



As the crassatella advances in age the 

 valves become very greatly thickened, 

 from which circumstance it obtains its 

 name. Cuvier places this genus in 

 the family Mytilacia, order Acephala ; 

 Lamarck in the family Mactracea ; and 

 De Blainville in the family Conchacea. 

 Recent crassatellse inhabit sandy mud at 

 depths varying from eight to twelve fa- 

 thoms. Some species of fossil crassa- 

 tellee have been found in the tertiary for- 

 mations. 



CRA'TER. (cratere, Fr. KpctTrip, Gr 

 KpciTrjpeQ, montip foramina, quibus igni 

 cinisgue evomitur.~) The basin-shapec 

 hollow in volcanic mountains whence 

 issue the flames and erupted matter. 



CRATE'RIFORM. (from crater and forma 

 Lat.) Hollowed out like a crater; o 

 the form of a crater ; bowl-shaped. 



CREMA'TION. (crematio, Lat.) A burning 



RE'NATE. ^(crenatus, Lat.) Notched 

 /RE'NATED. } at the margin ; scolloped ; 

 indented. 



1 . It is applied to leaves when the notches 

 or teeth on the borders are rounded, and 

 the notches not directed to either end of 

 the leaf. 



2. In entomology, a margin with inden- 

 tations, not sufficient to be called teeth, 

 the exterior whereof is rounded. 



RE'NATURE. The notch or indentation of 

 a leaf. 



CRENA'TULA. (from crenatus, Lat.) This 

 name has been given to this genus of bi- 

 valves from the hinge showing a row of 

 roundish or oval pits, making it appear as 

 if crenulated. An irregularly formed flat 

 bivalve ; closed, not giving passage to any 

 byssus ; the hinge linear, excavated, and 

 crenulated ; umbones terminal. It is 

 found in sponges, and moored to coral- 

 lines, &c. Parkinson, in describing the 

 crenatula, says, "there are very few 

 among the fossil shells of this or of any 

 other country, which, at first sight, are 

 more dissimilar from any of the recent 

 shells than the fossil crenatula. It is 

 very rarely found. 



CRE'NTILATE. ^ (crenels', Fr.) Indented 



CRE'NULATED. $ round the margin with 



small notches. The fine saw-like edge of 



the shell of the cockle, which so nicely 



fits into the opposite shells, is a familiar 



example of a crenulated margin. 



CRE'PITATE. (crepito, Lat.) To crackle. 



CREPITA'TION. (crepitation, Fr.) A low 



crackling noise. 

 CRE'SCIVE. (from cresco, Lat.) Grow- 

 ing ; increasing. 

 CRE'TA. (Lat.) Chalk ; carbonate of 



lime. 

 CRETA'CEOUS. Having the qualities of 



chalk ; containing chalk ; chalky. 

 CRETA'CEOUS GROUP. This group com- 

 prises the different strata from the chalk 

 of Maestricht to the lower green-sand 

 inclusive. In Lyell's Principles, they are 

 thus arranged: 1. Maestricht beds; 2. 

 Chalk with flints; 3. Chalk without 

 flints ; 4. Upper green-sand ; 5. Gault ; 

 6. Lower green-sand. The whole of these 

 formations are marine. 

 CRI'CHTONITE. The name given to a 

 black, opaque, shining mineral, after Dr. 

 Crichton. 

 CRIO'CERATES. A genus of ammonites, 



having the whorls disconnected. 

 CRINI'GEROUS. (from criniger, Lat.) 

 That hath much hair ; hairy ; overgrown 

 with hair. 



CRI'NITE. (crinitus, Lat.) Having tufts 

 of hair ; having the hair long, slender, 

 and dispersed. 



CRINO'IDAL. Containing fossil crinoidean 

 remains. The Derbyshire encrinital 



