CRUSTACEA. Aquatic arthropoda usually with two pairs of antenna on the head and breathing by gills. 



Class i. ENTOMOSTRACA. Small Crustacea with a variable number of segments and appendages. Larva, when 



present, has the Nauplius form. 

 Order i. PHYLLOFODA. Entomostraca with leaf-like swimming feet and usually a carapace or bivalve shell 



formed by a reduplication of the skin. Ex. Apus, Daphnia. 

 Order 2. OSTEACODA. 

 Order 3. COPEPODA. Entomostraca without shell-forming reduplication of the skin. Swimming feet biramous. 



Abdomen without appendages. Ex. Cyclops. 



Order 4. CIRRIPEDIA. Fixed and for the most part hermaphrodite Entomostraca with indistinctly segmented * 

 body enclosed by a reduplication of the skin and a calcareous valved shell. Usually six pairs of 

 biramous thoracic appendages. Ex. Lepas, Balanus, Sacculina. 

 Order 5. TRILOBITA. Palaeozoic Entomostraca with one pair of antennae. 



Class 2. MALACOSTRACA. Crustacea with a definite number (20) of segments and appendages. Larva when present 



usually has the Zooea form. 

 Order i. ARTHROSTRACA (Edriopfcthalmata). Malacostraca with sessile eyes, one pair of maxillipeds, seven 



free thoracic segments, without thoracic carapace. 

 Sub-order i. Amphipoda. Ex. Gammarus. 

 Sub-order 2. Isopoda. Ex. Oniscus, Asellus. 

 Order 2. THORACOSTRACA (Podophthalmata) . Malacostraca with eyes which are often stalked ; with a 



dorsal shield which connects all, or at least the anterior thoracic segments with the head. 

 Sub-order i. Cumacea. 

 Sub-order 2. Stomatopoda. Ex. Squilla. 

 Sub-order 3. Schizopoda. Ex. Mysis, Euphausia. 

 Suborder 4. Decapoda. Ex. Astacus, Cancer. 



