APPENDIX 201 



Subdivision 2. Arthrostraca. Malacostracans with usually seven 

 free thoracic body-segments, and with sessile eyes. 



Order 1. Amphipoda. Laterally compressed arthrostracans with 

 gills on thorax. Ex. Gammarus. 



i Order 2. Isopoda. Dorso-ventrally depressed arthrostracans with 

 ills on the abdomen. Ex. Oniscus. 

 Subdivision 3. Thoracostraca. Malacostracans with carapace cov- 

 ring the head and all or some of the thorax, and with stalked eyes. 

 Order 1. Schizopoda. Small thoracostracans with carapace covering 

 ntire thorax, and with one pair of maxillipeds. Ex. Mysis. 

 Order 2. Stomatopoda. Thoracostracans with three free thoracic 

 body-segments and large abdomen. Ex. Squilla. 



Order 3. Cumacea. Small thoracostracans with reduced carapace. 

 Ex. Diastylis. 



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. 



Class 2. Arachnoidea. Arthropods lacking antennae and with body 

 usually consisting of cephalothorax and abdomen. 



Division 1. Xiphosura. Large marine arachnoideans with a long, 

 spike-like telson. Ex. Limulus. 



Division 2. Arachnida. Usually air-breathing arachnoideans with 

 six pairs of appendages. 



Order 1. Scorpionida. Large arachnids with a long segmented 

 abdomen ending in a poisonous sting. Ex. Scorpio. 



Order 2. Palpigradi. Minute arachnids with a long, segmented 

 caudal filament. Ex. Koenenia. 



Order 3. Pedipalpi. Arachnids with a constriction between the 

 cephalothorax and the segmented abdomen. Ex. Thelyphonus. 



Order 4. Solifugse. Arachnids with a constriction between the 

 head and thorax. Ex. Galeodes. 



Order 5. Pseudoscorpionida. Arachnids without a constriction 

 between cephalothorax and abdomen ; pedipalps chelate and very 

 long. Ex. Chelifer. 



