236 VOCABULARY. 



meDt epithelium, and perhaps by the parietal layer of the 

 arachnoid membrane. 7'ftW. 



E. 



ECON'OMY. By the term 'animal economy' is understood the 

 aggregate of the laws which govern the organism. The word 

 economy is also used for the aggregate of parts which con- 

 stitute man or animals. 



EDENTA'TA. In natural history, an order of animals that are 

 destitute of front teeth, as the armadillo and ant-eater. Bell. 



EDEN'TULUS. One without teeth. 



EM'BRYO. The fecundated germ, in the early stages of its de- 

 velopment in utero. At a certain period of its increase, the 

 name ' fetus' is given to it, but at what period is not deter- 

 mined. Generally, the embryo state is considered to extend 

 to the period of quickening. 



ENCEPHALI'TIS. This term has been used by some nosologists 

 (classifiers of diseases) synonymously with ' cephalitis ' and 

 'phrenitis.' By others it has been appropriated to inflam- 

 mation of the brain, in contradistinction to that of the mem- 

 branes. 



E'OCENE. In geology, a term applied to the earlier tertiary de- 

 posits, in which are a few organic remains of existing species 

 of animals. Hence the term eocene (recent), which denotes 

 the dawn of the existing state of things. 



Dana. Lyett. Mantell. 



In America the eocene strata contain numerous fossils, 

 mostly marine mollusks, but also include some gigantic ver- 

 tebrates, a carnivorous cetacean seventy feet in length, and a 

 shark of which the teeth are sometimes six inches in length. 

 The Wyoming beds have furnished the remains of a remark- 

 able group of mammals, which are thought by Prof. Marsh 

 to form a new order, and which he has named * Dinocerata.' 

 The largest of these (Dinoceras mirabilis) had the bulk of an 

 elephant, and was provided with three pairs of horns and a 

 pair of great saber-like canine teeth. Johnson's N. U. Cyc. 



EPIDER'MIS. A modification of the epithelium, molded to the 

 papillary layer of the true skin ; composed of agglutinated, 

 flattened cells, which are developed in the liquor sanguinis,' 

 the latter being poured out on the true skin's external sur- 

 face. In the deeper layers the cells are rounded or columnar, 



