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MOLLUSOA. 



THE class Mollusca pulpy animals forms a grand division which man 

 has been pleased to make in the animal kingdom, and immediately 

 below the Vertebrata and above the Anmilosa, which again stand 

 above the Coelenterata, which includes the polyps, sea-anemones, 

 hydras, and corals, which last are more highly organized than the 

 Protozoa. 



The Mollusca may be divided into two groups, the Mollusca proper 

 and the Molluscoida. The mollusc proper, as represented in Fig. 120, 

 presents the following parts, and is supposed to be bilaterally sym- 

 metrical. H, is the haemal parts, in which the heart is situated, 

 commonly called the dorsal part, although the word is used in a 

 different sense in different divisions of the animal kingdom. In the 



Fig. 120. P. C. Mollusca. 



same manner the opposite region (N) is not termed the ventral, but 

 the neural part, in philosophical anatomy. It is the region in which 

 the great centres of the nervous system are placed. The termination 

 (a) is the anterior or oval part ; the other end (6), the posterior or 

 anal part: between these extremities the intestines take a straight 



