INVERTEBRATE ANIMALS. 59 



animal about an inch in length, constituting, according 

 to Professor Huxley, the class Ch^tognatha. For- 

 merly included with the Infusoria, but now generally 

 regarded as a sub-class of Scolecida, occur the Roti- 

 FERA or wheel-bearing animalcules, familiar, and from 

 their extreme beauty a source of high gratification, to 

 all microscopist observers of pond life. Rotifera and 

 TuRBELLARiA possess a " water-vascular system." 



5[ Coloured drawings of Planaria, Sagiita, and 



Rotifers, including Melicerta and Floscularia. 



Diagrams illustrating the biology of the group. 



Jfoutlc^ntlj Cable Case. 



The Mark ^ indicates specimens or other illustrations exhibited in the Cases. 



Sub-kingdom ANNULOSA. 



Animals composed of numerous annular somites or 

 segments arranged longitudinally. 



Province ANARTH ROPODA. 



Multisegmental WORMS (Rolleston). 



The Cn^TOGNATHA being removed to the Annuloida, on authority as given 

 above, this Province includes a single Class only. 



Class ANNELIDA. 



The only systematic work on the species of the ivhole class known to the 



Writer is "Histoire Naturelle des Auneles marins et d'eau douce." 



M. A. De Quatbbfageb. 3 vols. Svo. and 1 vol. of plates, About 



1,200 species are described. 



No Annelide has a heart or a head comparable with 



these organs as found amongst Crustaceans or Insects. 



The water-vascular system generally present in the 



Annuloida is here replaced by a pseudo-hsemal system 



conveying a fluid sometimes corpusculated. The lateral 



appendages of the segments, when present, are not 



articulated, but pertain to the skin. 



