Invertebrate Gallery of the Indian Museum. 7 



segmented Round-worms, of which the common Intestinal 

 worm may be taken as a type ; (3) the Annelida or 

 Segmented worms, of which the common Earth-worm may 

 be taken as a type ; (4) the Arthropoda or Segmented 

 animals with many-jointed legs, of which the common 

 Prawn may be taken as a type ; (5) the Echinodermata^ 

 of which the Star-fish may be taken as a type ; (6) the 

 Mollusca, of which the common Snail may be taken as a 

 type ; and (7) the Vertebrata, or animals which possess at 

 some tim.e of their life either a backbone or the element 

 out of which a backbone is developed, of which the Fish, 

 the Frog, the Crocodile, the Bird, and the Mammalian 

 quadruped are types. 



The old Lamarckian classification of animals is into 

 (i) Vertebrata and (2) Invertebrata — the latter including 

 the Protozoa^ the Ccelenterate Metasoa, and all the Coslo' 

 mate Metasoa, with the exception of that portion of the 

 Vertebrate phylum which consists of animals charac- 

 terized by a well-developed backbone. 



PROTOZOA. 



[(JDccu^Jging the Southern enb of OTasc I oxx ih.z Wizsiztw siic 

 of the (ialUrg]. 



The Protozoa are microscopic animals which consist 

 of a single cell, in other words of a single minute speck 

 of protoplasm, usually with a nucleus, sometimes with 

 several nuclei, but occasionally {Monera) without a 

 nucleus, and the great majority of them therefore can only 

 be represented in a Museum collection by enlarged models 

 and drawings. 



Many species, however, are able to secrete protective 

 shells of chitin or of lime or of flint, or to manufacture 

 tests by the agglutination of minute grains of sand, and 

 some of these are large enough to be distinguished by the 

 naked eye. 



