XII. — CRUSTACEA AND LOWER INVERTEBRATA. 91 



XII. 



CRUSTACEA AND LOWER INVERTE- 



BRATA. 



The title adopted for this chapter is rather comprehensive ; it is 

 intended to include all the Invertebrata other than Mollusca and 

 Insects, viz: — Part of the Arthropoda, the Vermes (or' Worms), 

 the Echinodermata, the Ccelenterata, and the Protozoa. The 

 detailed classification of these will be found on page 19. A 

 short description can only be given here. The specimens on view 

 are in the room at north-end of upper floor. 



Sub-Kingdom IL— ARTHROPODA. 



Class I. — INSECTA has already been considered — see 

 Chapter XI. 



Classes II and III.—MYRTAPODA and ARACHNIDA 



are passed over in the meantime. Specimens are to be seen in 

 Case 17. 



Class IV.— CRUSTACEA.— The members of this class 

 chiefly inhabit water ; they breathe for the most part by gills ; 

 the body is divided into hea.d, thorax, and abdomen ; as a rule 

 the head is fused with one or more of the thoracic segments, 

 forming the cephalothorax. The head carries two pairs of 

 antennge, and the other appendages (legs, &c.) are carried by 

 the thorax and abdomen. The Crustacea are divided into eight 

 sub-classes ; some of which, however, are too small for exhibition 

 in the cases. It will, therefore, be unnecessary to describe such 

 as are not represented in the collection. 



