INVEBTEBRATE ANIMALS. 57 



animal about an inch in length constituting, accord- 

 ing to Professor Huxley, the class Ch^tognatha. 

 Formerly included with the Infusobia, but now gene- 

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

 RoTiFEBA or wheel-bearing animalcules, familiar, and 

 from their extreme beauty a source of high gratification, 

 to all microscopist observers of pond-life. Rotifeba 

 and Tubbellabia possess a " water-vascular system." 

 IT Coloured drawings of Planaria, Sagitta, and 

 Rotifers, including Melicerta and Floscularia. 

 Diagrams illustrating the biology of the group. 



The Mark IF indicates specimens or other illustrations exhibited in the Oases. 



Sub-kingdom ANNULOSA. 



Animals composed of numerous annular somites or 

 segments arranged longitudinally. 



Province ANARTH ROPODA. 



Multisegmental WORMS (Rolleston). 



The Chjetognatha being removed to the Annuloida, on authority as given 

 above, this Province includes a single Glass only. 



Class ANNELIDA. 



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

 the Writer is " Histoire Naturelle des Anneles Marins et d'eau 

 douce." M. A. Db QuATREFAGES. B vols. 8vo. and 1 vol. of plates. 

 About 1200 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. 



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