E B U 



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E C H 



eboulement, from the verb ebouler. 

 Bakewell. 



EBULLI'TION. (ebullitio, Lat. ebullition, 

 Fr. ebollizione, It.) Intestine motion or 

 agitation, occasioned by the struggling of 

 particles of different properties ; boiling 

 or bubbling. 



EBU'RNA. (from eburmis, Lat. ivory.) 

 An oval or elongated univalve with a 

 deeply umbilicated columella ; the aper- 

 ture oblong, and notched at the bottom. 

 The recent eburna lives in sandy mud. Fos- 

 sil eburnse are rarely met with. Parkinson 

 states that Lamarck does not notice them 

 among the Paris fossils, but that a shell 

 exists among the Essex fossils which he 

 names Eburna glabrata. Dr. Mantell 

 gives eburna as a fossil of the chalk mark, 

 but affixes a note of interrogation to it, as 

 though doubtful. 



ECCE'NTRIC. See Excentric. 



ECCENTRI'CITY. See Excentricity. 



ECCHYMO'SIS. (gKxv/iwo-ic, Gr. sanguinis 

 subcutem per grumos effusio.) A dark 

 spot on the skin, caused by an extravasa- 

 tion of blood. 



ECHI'DNA. (txtfiva, Gr.) A genus of 

 quadrupeds belonging to the order Mono- 

 trema, an order comprising only two 

 genera, the Ornithorhynchus and Echidna. 

 The spiny ant-eater of New Holland, a 

 land quadruped, with a peculiar construc- 

 tion of clavicles and furcula. There are 

 two species, echidna hystrix, or spiny 

 echidna, and echidna setosa, or bristly 

 echidna. 



ECHI'NATE. ) (echinatw, Lat.) Bristled 



E'CHINATED. S like a hedge-hog ; set 

 with spines ; having sharp points or 

 spines. 



ECHI'NIDAN. A fossil belonging to the 

 class Echinoderms. Prof. Buckland states 

 that the family of Echinidans appears to 

 have extended through all formations, 

 from the epoch of the transition series to 

 the present time. 



ECHI'NITE. The fossil echinus, or sea- 

 urchin. Echinites vary greatly both in 

 form and structure, and are arranged 

 accordingly into many sub-genera ; they 

 are all marine. The chalk formation 

 abounds with these fossil shells, some of 

 which are exceedingly beautiful from 

 their elegant and minute decorations. 

 The Ananchytes cretosus, a sub-genus, 

 is found in some places in shoals, and in 

 every condition from the youngest to the 

 oldest age. The Spatangus cor-marinum, 

 another sub-genus, silicified, is frequently 

 found on our shores and in our gravel- 

 pits, and the spines of the different sub- 

 genera, detached from the shells, are 

 very numerously dispersed throughout 

 the chalk. 



ECHI'NUS. (echinus, Lat. i\ivoG, Gr.) 



The sea-urchin, or egg. The echinus 

 is included in the order Echinodermata, 

 being covered by a hard and coriaceous 

 skin. The shell is spherical, and com- 

 posed of polygonal plates, closely fitted 

 to each other, and has attached to it 

 many spines or prickles, which serve as 

 instruments of motion. Some species of 

 the echinus are edible, more especially 

 the E. Esculentus. The echinus feeds 

 principally on small shell-fish, which it 

 seizes with its feet. 



ECHINODER'MATA. } (from iylvoQ, and 

 ECHI'NODERMS. $ fo'pjua, Gr.) An 

 order of radiated animals, including the 

 Echinus, or sea-urchin ; the Asterias, or 

 star-fish ; the Holothuria, and the Si- 

 phunculus. The skeletons of the animals 

 of this class are generally in the form of 

 extemal crusts, or shells, covered with 

 projecting spines. Echinoderms extend 

 through all the formations, from the 

 epoch of the transition series to the pre- 

 sent time. They are composed of the 

 carbonate, mixed with a small, but va- 

 riable, proportion of the phosphate of 

 lime, and are hardened by animal matter. 

 Of the radiated animals, Cuvier states that 

 the Echinodermata are the most compli- 

 cated. He divides them into two orders : 



1. The Pedicellata, or those furnished 

 with feet, or with vesicular organs ful- 

 filling the functions of feet. 



2. The Apoda, or those destitute of the 

 vesicular organs of progressive motion 

 which the Pedicellata possess. 



In the first order he places the Asterias, 

 Encrinus, Echinus, and Holothuria ; in the 

 second, or Apoda, the Molpadia, Minyas, 

 Priapulus, Lithodermis, Siphunculus, Bo- 

 nellia, and Thalassema. Agassiz has re- 

 cently shown, contrary to the opinion 

 always previously entertained, that the 

 rays of Echinoderms are dissimilar, and 

 not always connected with a uniform 

 centre ; and that a bilateral symmetry, 

 analogous to that of the more perfect 

 classes of animals, exists throughout the 

 different families. 



ECHINA'NTHUS. The name given to a 

 section of Catocysti by Leske. The 

 genus echinanthus comprises all the 

 echinites of this section. Of this genus 

 there are many species, namely, Echinan- 

 thus humilis, Ech. altus, Ech. ovatus, 

 Ech. orbicularis. The echinanthus was 

 named Scutum by Klein. The shells are 

 of an irregular figure, resembling a buck- 

 ler. On the base, which is concave, five 

 grooves pass from the margin, and ter- 

 minate at the mouth iu the centre. Five 

 rays ornament the upper part. The 

 mouth is placed in the centre of the base, 

 and is of a pentagonal form. The whole 

 of the surface is marked with very small 



