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seem to have been superior, if 

 equal, to that now experienced 

 between the tropics. 



The English Eocene deposits are 

 generally conformable to the chalk, 

 being horizontal where the beds of 

 chalk are horizontal, and vertical 

 where they are vertical; so that 

 both series of rocks appear to have 

 participated in nearly the same 

 movements. 



As a summary of the preceding, 

 the numerical proportion of recent 

 to extinct species of fossil shells, in 

 the four different tertiary periods, 

 is as follows : 



Newer Pliocene period 90 to 95 

 Older Pliocene period 35 to 50 

 Miocene period . . 18 

 Eocene period . . 3J 

 per centum of recent fossils. 



In the British Islands, strata 

 belonging to the Eocene system 

 are found only in the South Eastern 

 parts of England, namely, in the 

 country round London, in the 

 south of Hants, and in the north of 

 the Isle of Wight. The Eocene 

 system consists of the following 

 groups, Lower Eocene, containing 

 the Plastic Clay, the "Woolwich 

 Beds, Thanet Sands, London Clay, 

 and Bognor Rock, all fresh- water. 

 The Middle Eocene, the Bagshot 

 and Bracklesham Sands, the Barton 

 Clays, marine, and the Headon, 

 fluvio - marine and fresh - water. 

 The Upper Eocene, containing the 

 St. Helen's Sands, the Bembridge 

 Sands, and the Hampstead series, 

 principally fresh-water. Of the 

 Pleiocene group there is a sub- 

 division, named Pleistocene, or the 

 maximum proportion of the recent, 

 containing from 90 to 95 per cent, 

 of the recent, and after these has 

 been added the "Post Pleiocene, 

 or Quarternary," in which all the 

 fossil shells are still found living, 

 though not perhaps in the imme- 

 diate neighbourhood of the places 

 where they are found fossil. 



EPHE'MEBA. (c^fiepla, ex. W et 

 yijiepa, Gr.) Insects, so called 

 from their short term of life in 

 their perfect state. Their body is 

 extremely soft, long, tapering, and 

 terminated posteriorly by two or 

 three long and articulated seta?. 

 The antenna? are very small and 

 composed of three joints, the last 

 of which is very long, and in the 

 form of a conical thread. The 

 ephemera usually appear at sun- 

 set, in fine weather, in summer 

 and autumn, along the banks of 

 rivers and lakes. The continuation 

 of their species is the only function 

 those animals have to perform, for 

 they take no food, and frequently 

 die on the day of their metamor- 



Ehosis. In another condition, as 

 irvae, their existence is much 

 longer, extending from two to 

 three years. In this first state 

 they live in water. 



E'PICABP. (from fVt, upon, and *ra/j- 

 7T09, fruit, Gr.) In botany, the 

 outer skin of fruits is called the 

 epicarp; the fleshy substance, or 

 edible portion, is termed the sarco- 

 carp, and the stone is called the 

 endocarp. 



EPIDE'RMAL. } Composed of epidermis; 



EPIDE'BMIC. ) relating to the epi- 

 dermis ; resembling the epidermis. 



EPIDE'BMIS. (eirideppls, Gr. epidermis , 

 Lat. epiderme, Er. epidermide, It.) 

 The scarf-skin, or cuticle, of animals. 

 In conchology, the outer skin or 

 cuticle, with which the exterior 

 surface of many of the univalve and 

 bivalve shells is covered. It is 

 membranaceous, and resembles the 

 periosteum which covers the bones 

 of animals. The skin seems to be 

 formed entirely by the animal, and 

 is always met with in some species, 

 and never in others; those shells 

 with a ragged surface have almost 

 always an epidermis. In some it is 

 laminated, velvety, fibrous, or 

 rough; in others it is thin and 

 pellucid, allowing the colours of the 



