A N N U L OS A. 



CHAPTER XXVIII. 



ANNULOSA. 



i. GENERAL CHARACTERS OF ANNULOSA. 2. GENERAL 

 CHARACTERS OF ANARTHROPODA. 3. CLASS GEPHYREA. 

 4. GENERAL CHARACTERS OF THE CLASS ANNELIDA. 



SUB- KINGDOM ANNULOSA. The members of this sub-kingdom 

 are distinguished by the possession of a body which is composed 

 of numerous segments, or " somites" arranged along a longitudinal 

 axis. 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 (Esophagus (fig. 75). The limbs 

 (when present) are turned towards the neural aspect of the body. 



The sub-kingdom Annulosa may be divided into two primary 

 divisions, according as the body is provided with articulated 

 appendages, or not ; these divisions being termed respectively 



Fig- 75- Diagram of an Annulose Animal, a Blood-vascular or haemal system ; 

 b Digestive system ; <: Neural system. 



the Arthropoda and Anarthropoda. The first of these com- 

 prises Crustaceans, Spiders, Scorpions, Centipedes, and Insects : 

 whilst the latter includes the Spoon-worms, Leeches, Earth- 

 worms, Tube-worms, and Sand -worms. 



DIVISION I. ANARTHROPODA. In this division of the Annu- 

 losa the locomotive appendages are never distinctly jointed or arti- 

 culated to the body. In this division are included three classes 

 viz., the Gephyrea, the Annelida, and the Chcetognatha. 



CLASS I. GEPHYREA ( = Sipunculoided). This class includes 

 certain worm -like animals in which the body is sometimes 



