APPENDIX 185 



Suborder 2. Cladocera. Laterally compressed phyllopods, the 

 body of which is not distinctly segmented and is enclosed in a 

 bivalve shell ; second pair of antennae are swimming organs and 

 project from shell. Ex. Daphnia. 



Order 2. COPEPODA. Elongated entomostracans with usually 

 distinctly segmented body and no gills ; the female often bears a 

 pair of egg-sacs. Ex. Cyclops. 



Order 3. OSTRACODA. Minute laterally compressed entomos- 

 tracans with entire body enclosed in bivalve shell. Ex. Cypris. 



Order 4. CIRRIPEDIA. Sessile, hermaphroditic entomostracans 

 with body enclosed in a calcareous shell ; barnacles. Ex. Lepas. 



Division II. MALACOSTRACA. Crustaceans with a constant 

 number (20) of body -segments and nineteen pairs of appendages ; 

 abdominal appendages present. 



Subdivision I. PHYLLOCARIDA (LEPTOSTRACA). Primitive mala- 

 costracans with carapace and leaf-like thoracic feet. Ex. Nebalia. 



Subdivision II. ARTHROSTRACA. Malacostracans with usually 

 seven free, thoracic body-segments and sessile eyes. 



Order 1. AMPHIPODA. Laterally compressed arthrostracans 

 with gills on thorax. Ex. Gammarus. 



Order 2. ISOPODA. Dorso-ventrally depressed arthrostracans 

 with gills on abdomen. Ex. Oniscus. 



Subdivision III. THORACOSTRACA. Malacostracans with cara- 

 pace covering head and all or some of the thorax, and with stalked 

 eyes. 



Order 1. CUMACEA. Small thoracostracans with reduced 

 carapace. Ex. Diastylis. 



Order 2. STOMATOPODA. Thoracostracans with three free 

 thoracic body-segments and large abdomen. Ex. Squilla. 



Order 3. SCHIZOPODA. Small thoracostracans with carapace 

 covering entire thorax, and without maxillipeds. Ex. Mysis. 



Order 4. DECAPODA. Large thoracostracans with carapace 

 covering entire thorax, and with three pairs of maxillipeds. 



Suborder 1. Macrura. Elongated decapods with large abdomen. 

 Ex. Homarus. 



Suborder 2. Brachyura. Broad decapods with reduced abdomen. 

 Ex. Cancer. 



