300 THE 



deposits. We would refer the reader to the chart on page 194, 

 where these divisions will appear marked according to Dr. Buck- 

 land, under the names primary, transition and secondary, and 

 tertiary. It will only bo passible to give a very superficial sketch 

 of the probable condition of our planet during these several 

 epochs, but we shall endeavor to convey a clear idea of the suc- 

 cession of animal and vegetable life which so strongly character- 

 izes them, so that the reader will be prepared to enter upon a 

 more extended investigation. 



It is almost impossible even when writing upon ordinary topics^ 

 to avoid the use of technical terms, and perhaps least of all can 

 this use be avoided, when natural history becomes the subject. 

 There is nothing of so much benefit, both in economising the 

 time of the student,and in assisting his memory, as a correct and 

 intelligible system. A well selected name, expressive of pecu- 

 liar characters, or habits, or localities, conveys a multitude of 

 ideas to the mind, which a common or vulgar name would en- 

 tirely fail to do, for this reason we shall use the names generally 

 applied by geologists to the several fossils, giving in all cases, 

 their meaning or translation, whenever these words are derived 

 either from the Greek or Latin. The word fossil, which we have 

 often used, meant originally, what was dug out of the earth, it is 

 now however applied only to the remains of organic matter. 

 The fossil animal kingdom may be divided into six sections. 



I. INFUSORIA, or Animalcules. The name infusoria is derived 

 from the presence of many genera, or groups of species, in vege- 

 table infusions, not easily observable without the microscope. 



II. ZOOPHYTES, or Animal Vegetables, a term applied to corals 

 and other animals supposed to resemble plants; the subdivisions 

 of this group are, 



1. AMORPHOZOA, or animals of no regular shape like sponges and 



2. POLYPARIA, or many producing animals as the corals. 



III. ECHINODERMA, or spiny skinned animals, subdivided into, 



1. CRIKOIDEA, or Encrinital, i. e. lily or cup-shaped animals. 



2. ATERIA, or btar'formed, like the star-fish. 



3. ECHLXIOA, or spiny animals* like the sea-urchin, or sea-egg;. 



