CRUTCHED FRIARS 



CRYPT 



EOT 



(Macrura) e.g. Crayfish (q.v.), Lolwter ; short- 

 tuileil ( lirachyura), Cralis. 



Distribution in X/Ki<-e, and Time. (a) Deep- 

 sea forms are very abundant, and often remarkable 

 'for their colossal size, their bizarre forma, and 

 brilliant red colouring.' Blind species ore known 

 t<> <.rc-iii in the depths, and others are brilliantly 

 phosphorescent, (o) Pelagic surface Crustaceans 

 (especially Schizopods and Entomostraca ) are very 

 aliumlaiit, ami often form a large part of the food 

 of ti>hes. They are often beautifully transpar- 

 ent, and hardly to be seen in the water. Less 

 frequently they are brilliantly coloured (as in 

 Sapphirina) or phosphorescent. Some of them are 

 remarkable for their large eyes. One Arnphipod 

 Crustacean presents a curious mimicry of a Modu- 

 s'. i. I form. Decapods are most abundant in the 

 wanner waters, (c) Crustaceans form an important 

 part of the relatively sparse and uniform fauna of 

 lakes. They occur both on the surface and at the 

 bottom, the latter being generally more sluggish. 

 The surface forms, at anyrate, are usually per- 

 fectly transparent, with the exception of the eye. 

 (<I) The catalogue of terrestrial Crustaceans, which 

 includes species of Amphipods, Isopods, and Deca- 

 pods, is relatively a very short one. 



The Crustacea date back to Cambrian times, but 

 the highest forms (Decapods) were not firmly 

 established till the Tertiary period. Some 800 

 fossil species, as against over 5000 living forms, are 

 known. Some of the genera e.g. Estheria from 

 the Devonian, are marvellously persistent, and 

 survive from ancient epochs as still very successful 

 and widely distributed forms. The Trilobites 

 (q.v.) are not now regarded as true Crustaceans. 

 (For distribution, see Heilprin, Inter. Sc. Series, 

 1887.) 



Pedigree. It is usually believed that Crustacea 

 are descended from a 'primitive Phyllopod-like 

 ancestor, and this from a segmented worm-type. 

 The very constant occurrence of a Nauplius larva 

 has led zoologists to regard it as representing a 

 remote ancestor. The lines of differentiation chiefly 

 consisted in the development and manifold modifi- 

 cation of the fundamentally similar appendages, 

 and in the perfecting of the exoskeleton as a base 

 for muscular attachment. (See Herdman's Classi- 

 fication of Animals, Lond. 1885.) 



Economic Importance. Crabs, lobsters, crayfish, 

 shrimps, prawns, &c. form part of our food-supply. 

 Others are indirectly useful as important parts of 

 the food of herrings and other lisnes. Many are 

 doubtless useful in purifying the water from 

 organic debris, while others are the hosts of im- 

 portant parasites e.g. the Cyclops species, which 

 contains Dracuticulus metlinenis. 



See ACORN-SHELLS, BARNACLE, BRINE-SHUIMP, CIRRI- 



PKDIA, COPEPODA, CRAB, CRAYFISH, CtPRIS, CYCLOPS, 



LOBSTER, PRAWN, SHRIMP, WATER-FLEA, &c. ; also COM- 

 MENSALISM, PARASITISM, PARTHENOGKNKSIS, &c., and 

 references under above articles. For further details, 

 consult general text-books of Brooks (Boston, 1882), 

 Claus, Gegenbaur, Huxley, Rolleston and Hatchett 

 Ja-kson ; also Baird, British Enlomostraca ( Ray Soc. 

 1850); Balfour's Smbnolom; Bell, British Stalk-eiied 

 Crustacea (Lond. 1856); Challenger Reports (several); 

 Claus, (fentaloiiii of Crustacea (187(5); Dana, Crustacea 

 of U.S. Exploring "Expedition (Phila. 1852); Gerstwcker 

 in Bronn's Thierreich ; Huxley's Cratifislt ( 1881 ) ; Milne- 

 Edwards, Histoire Naturelle det Crustaces ( Paris, 1834- 

 40); the Monographs of the Naples Station (several); 

 F. M tiller, Facts for Danmn (1869); San, Frtsh-water 

 Crustacea of Aforway ( Christiania, 1867 ) ; Spence Bate 

 and "VVestwood, British Sessile-eyed Crustacea ( 1863-68} 

 Stebbing, A History of Crustacea ( 1893 ). 



Crntched Friars* an order of friars, carry- 

 ing in their hand a staff, on the top of which 

 was a cross, received the name of Croisicrs (Fr. 

 ix t ' cross ' ), corrupted into Crouched or CrutcJied 



Friars. They came to England in the 13th century, 

 and had monasteries in London ( which still given 

 name to a street), Oxford, and licigate. 



Cruveilhier, JKAN, physician, horn at 

 Limoges in 1791, became professor of Pathology 

 at Montpellier in 1824, and of Pathological Ana- 

 tomy in Paris in 1836. Besides his great work, 

 Anatomie Patholoaiuue du Corps Humain (2 vols. 

 1828-42), he published several other works on 

 anatomy, which were for many years the most 

 valuable French contributions to their subject, 

 and also a Life of Dupuytren (1840). He died 6th 

 March 1874. 



Crwth ( pronounce the w as French u ), an old 

 Welsh stringed instrument. Four of its six strings 

 were played with a bow, the other two being 

 twitched by the thumb. 



Cryolite* a mineral which exists in great abund- 

 ance on the coast of Greenland. It consists mainly 

 of a fluoride of aluminium in combination with 

 Fluoride of Sodium, 6NaF,Al 2 F 8 . The metal 

 Aluminium (q.v.) was formerly largely obtained 

 from it, but it is now most important as a source 

 of alum and of soda bicarltonate ; much of it, also, 

 is melted and made into a kind of glass. 



CryophorilS (Gr. kryos, 'cold,' and phero, 'I 

 carry ) is an instrument consisting of a glass tube 

 with a bulb at both ends, used for showing the 

 diminution of temperature in water by evapora- 

 tion. In constructing it the whole of the air is 

 extracted, leaving practically a vacuum inside. A 

 little water is present in one of the bulbs, and 

 when the second bulb, containing only water- 

 vapour, is placed in a freezing mixture, the vapour 

 condenses, which causes more vapour to rise from 

 the water in the first bulb. The result of this 

 vaporation from the first bulb is the abstraction of 

 much heat, and ultimately the remaining water 

 passes into a frozen state. 



Crypt ( Gr. krypto, ' I hide ' ). In the early days 

 of persecution the Christians were accustomed for 

 security to worship in the catacombs or crypts where 

 they buried their dead (see CATACOMBS). \Vhen 

 persecution ceased, this custom led to the erection 

 of churches over the graves of martyrs and saints ; 

 but at a later date the bodies of the saints were 

 transferred to chambers, constructed to resemble 

 the catacombs, under the sanctuary or altar of the 

 new churches, in order to add to their sanctity. 

 These crypts and their sacred shrines were visited 

 by numerous pilgrims, and were frequently con- 

 structed for the accommodation of the devotees, of 

 sufficient size to admit a number at a time, who 

 descended by one stair, and ascended by another. 

 In other cases the crypts were so placed that the 

 shrine of the saint could lie seen from the aisles of 

 the choir, the floor of which was necessarily raised 

 considerably above the level of the nave. Crypts 

 of these kinds were usual in the early centuries, 

 and many examples of them have l>een preserved in 

 Italy and France, even where the churches over 

 them have l>een rebuilt. The crypt of the Circular 

 church of St Benigne at Dijon was one of the 

 largest. There a great circular aperture in the 

 centre of the floor of the upper church enabled a 

 very large congregation of pilgrims, including those 

 in the crypt, to see the shrine of the saint, and 

 witness any ceremony taking place there. 



After the 13th century crypts were not so much 

 in use. The great cathedrals were regarded as 

 much in the light of civil as of ecclesiastical edifices, 

 and the floor of the choir was brought down to the 

 level of the rest of the building. It sometimes 

 happened that owing to the slope of the site con- 

 siderable underbuilding was required under the 

 choir, in which case an under church was con- 

 structed, which was called by the old name of the 



