INAUGURAL ADDRESS. 241 



4. Infusoria, or animalcules, include a large group, comprising 

 the most minute of living creatures, highly interesting to watch 

 during life, but not capable of being preserved satisfactorily. 



Following the Protozoa comes another great class — the Ccelen- 

 terata, or Radiata — comprising the Sea Anemones and Polyps, 

 nearly all of which are marine ; 'one, however, the Hydra, is often 

 found on water weeds, and therefore likely to come before you ; it 

 consists of a gelatinous body, with long tentacles encircling one 

 end, which wave about in the water, and clasp its prey. The 

 Echinoderms, or star fish and sea urchins are also all marine. 



The third great division, Annulosa, embraces animals whose 

 bodies are composed of rings, and bearing limbs in lateral pairs, 

 though in some these are absent. Lowest of these, and passing, as 

 it were, from the last group, are the Entozoa, or intestinal worms, 

 which have of late acquired considerable importance from the 

 number of human beings infested by them, and for our full know- 

 ledge of which we are entirely indebted to the microscope. Next 

 come the Annelida, or 7*ed-blooded worms, which have their organs 

 more developed, and in which we observe a differentiation of the 

 segments into a dorsal and ventral arch, each supporting appen- 

 dages. The Leech and Earthworm represent the lower forms of this 

 group ; and in the higher we have the beautiful Serpulae and other 

 tube-dwelling species, remarkable for the elegance of their plumed 

 tentacles. 



The Kotifera include many beautiful microscopic animals, which 

 were long united with the Infusoria, but stand far above them in 

 organisation ; with some of them you, no doubt, are familiar, as 

 captives in the dipping bottles so assiduously plunged into every 

 promising pool. Yet notwithstanding what Mr. Gosse has done 

 to elucidate their structure, much has still to be learned repecting 

 their life history. 



The Crustacea, well known to you by the crab, lobster, and 

 shrimp, also comprise many elegant minute species, which abound 

 in pools, and belong to the order Entomostraca — such as Daphnia, 

 Cyclops, Cypris, &c. — supplying interesting subjects for microscopic 

 investigation. 



Following these come the Arachnida, or spiders and mites, form- 

 ing the orders Araneida and Acarida, readily known by the 1st and 

 2nd divisions, or head and thorax, being united in one piece, and 

 by possessing four pairs of legs. Both groups are especially 

 worthy of investigation : the spiders, for the wonderful diversity 



