ANNULOSA: GEPHYREA. 



ANNUL O SA. 



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 cesophagus (fig. 52). 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 

 the Arlhropoda and Anarthropoda. The first of these comprises 

 Crustaceans, Spiders, Scorpions, Centipedes, and Insects ; 

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

 worms, Tube-worms, and Sand-worms. 



Fig. 52. Diagram of an Annulose Animal, a Blood-vascular or haemal system ; 

 b Digestive system ; c Neural system. 



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 Chcztognatha. 



CLASS I. GEPHYREA (Sipunculoidea). This class includes 

 certain worm-like animals in which the body is sometimes ob- 



VOL. I. M 



