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CHAPTER XVI. 



SUB-KINGDOM IV.ANNULOSA. 



FOSSIL ANNELIDA. 



SUB -KINGDOM ANNULOSA. The Annulose animals are dis- 

 tinguished by the possession of a body which is composed of 

 numerous segments arranged longitudinally one behind the other. 

 A nervous system is always present, and consists of a double 

 chain of ganglia running along the ventral surface of the body 

 and traversed anteriorly by the gullet. The limbs (when present) 

 are turned tovjards that side of the body upon which the chief 

 masses of the nervous system are situated. 



The sub - kingdom Annulosa may be divided into two 

 primary sections, according as the body is provided with 

 articulated appendages or not ; these divisions being known 

 respectively as the Arihropoda (or Articulata) and Anarthro- 

 poda. The first of these comprises the Crabs, Lobsters, and 

 the like (Crustacea), the Spiders and Scorpions (Arachnida), 

 the Centipedes and Millipedes (Myriapoda), and the true 

 Insects (Insect a). The latter comprises the Spoon- worms 

 (Grephyrea), the Arrow- worms (Chcetognatha), the Leeches 

 (Hirudinea), the Earth-worms (Oligochceta), the Tube-worms 

 (Tubicola), and the Sand- worms or Sea- worms (Errantia) ; 

 the last four groups constituting the class of the Einged 

 Worms or Annelida. 



Kegarded as a whole, the great Annulose sub-kingdom 

 seems to have commenced at least as early as the Echinodcr- 

 mata and the Ccelenterata. Both the Anarthropodous and 



