E P I 



E Q U 



of the Oxfordian group," Profes- 

 sor Catullo divides the Epiolitic 

 group, which consists of lime 

 stones, into the upper and lower, 

 the former composed of the red 

 lime stones of the Jura range, the 

 lower, the Epiolitic lime stone of 

 the Venetian Alps. 



EPI'PHYSIS. (eV/<?W/s, from eVt0va> f 

 Gr.) A process of bone attached 

 to a bone, but not being a part of 

 the same bone, as in the case of 

 apophysis. 



Epi'PLOON. (eVfVXooz/, from liriirKeia, 



Gr. epiploon, Fr.) The omen turn, 

 or caul ; that membranous expan- 

 sion which hangs from the bottom 

 of the stomach and covers the 

 intestines. 



EPIZOO'TIC. (from ITTI and woz>, Gr.) 

 Containing animal remains, as epi- 

 zootic hills, or epizootic strata. 



E'POCH. (eVo^, Gr. epocJia, Lat. 

 epoqm, Fr. epoca, It.) A term 

 literally signifying a stop, a fixed 

 point of time, from which succeed- 

 ing years are numbered; the period 

 at which a new computation, or 

 reckoning, is begun. 



EQUA'TOR. (equateur, Fr. cequator, 

 Lat. equatore, It.) A great circle 

 of the sphere, equally distant from 

 the two poles of the world, or 

 having the same poles with those 

 of the world. It is called the 

 equator, because when the sun is 

 in it, the days and nights are 

 equal ; whence also it is called the 

 equinoctial. Every point of the 

 equator is a quadrant's distance 

 from the poles of the world ; 

 whence it follows, that the equator 

 divides the spheres into two hemi- 

 spheres, in one of which is the 

 northern, and in the other the 

 southern pole. 



EQUATO'BIAL. Pertaining to the 

 equator: the equatorial diameter 

 of our planet exeeds its polar 

 diameter by about 26 miles; the 

 length of the equatorial diameter 



being 7927 miles, that of the polar 

 7900. 



EQUIA'NGULAR. (from aquus and an- 

 ffulus, Lat. equiangule, Fr. equian- 

 golo, It.) A figure whose angles 

 are all equal; consisting of equal 

 angles ; having equal angles. 

 EQUISETA'CE^. (from equisetum, horse- 

 tail.) These plants are known in 

 this country as the horse-tail of 

 our ditches. EquisetaceaB are found 

 fossil and recent. H. Ad. Brong- 

 niart has, in his "Histoire des 

 VSgetaux Fossiles," divided fossil 

 equisetacea3 into two genera ; the 

 one exhibits the characters of living 

 equiseta, and as a fossil is rare; 

 the other differs greatly in its form, 

 frequently attaining an immense 

 magnitude; these last have been 

 arranged under the distinct genus 

 Calamites. Equisetaceae are found 

 from Lapland to the Torrid Zone ; 

 the species are most abundant in 

 the temperate zone : as we approach 

 a more frigid temperature, they 

 diminish in size and abundance, 

 and in the warm and humid re- 

 gions of the tropics they acquire 

 their greatest magnitude. 

 EQUISETUM. (Lat. A genus of the order 

 Filices, belonging to the Crypto- 

 gamia class of plants.) Horse-tail. 

 Of this genus there are numerous 

 species. The equisetum fluviatile 

 of our marshes is the largest of all 

 the species, growing sometimes to 

 the height of three feet, and nearly 

 an inch in diameter. It has a 

 succulent, erect, jointed stem, with 

 attenuated foliage surrounding the 

 joints in whorls. In the coal 

 measures, remains of the equiseta 

 are in great abundance, and occur 

 of a magnitude quite unknown at 

 the present day, some of the stems 

 being fourteen inches in diameter. 

 M. Ad. Brongniart enumerates 

 twelve species of calamites and 

 two of equiseta found in strata of 

 the carboniferous series. Equiseta 

 occasionally occur in the Wealden 



