8 ELEMENTARY ANATOMY. [LESS. 



c., and all polyps, including many compound animals which 

 grow up in a tree-like manner, and the minute creatures 

 which by their secular existence have formed not only such 

 parts of the earth's surface as reefs and coral islands, but 

 even the State of Florida itself, of which they were un- 

 doubtedly the first founders. 



Lastly, we 1 nave the sub-kingdom PROTOZOA, r containing 

 all the lowest forms of animal life,, placed together rather 

 owing to the absence in them of characters possessed by 

 higher groups than from positive characters which they share 

 in common. 



Such are the Infusoria, 2 the sponges,, and those wonderful 

 Foraminifera 3 which took (and are taking at the bottom of the 

 Atlantic) so large a part in the formation of the chalk, and 

 therefore built up much of Old England itself. 



FIG. 7- A FORAMINIFER FIG. 8. ONE OF THE LOWEST PROTOZOA 



(Globigerind). (Protomoeba), after Haeckel. 



In the lowest grade of the animal kingdom is a creature, 

 Protogenesf at once structureless and devoid of any constant 

 form, as its shape varies like that of Proteus himself. A mere 

 morsel of semi-fluid jelly, floating in the ocean, it is destitute 

 of any organ,, even so much as a cell, and exhibits animality 

 in the last degree of structureless simplicity. 



The last six sub-kingdoms may very conveniently be taken 

 together,. and spoken of as the Inveriebrata, in contrast to the 

 highest sub-kingdom, from which in so many points the other 

 primary groups agree in differing. Thus we have the Verte- 

 brata on the one hand, and on the other the Invertebrata, 

 including the Mollusca, Annulosa, Molluscoida, Annuloida, 

 Ccelenterata, and Protozoa. 



IT. Having made this rapid survey of the whole animal 

 kingdom, it will be well to consider the general characters 



1 Protozoa, from TrpSrog, first ; vr>ov, animal. 



2 So called because found in infusions when left exposed to the air for a time. 



3 Foramina andferc, having holes or perforations. 

 < flpSTOj;, first ; "iivtvOai, to be born. 



