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. 
Order 2. Isopoda. Dorso-ventrally depressed arthrostracans with 
gills on the abdomen. Ex. Oniscus. 
Subdivision 3. Thoracostraca. Malacostracans with carapace cov- 
ering the head and all or some of the thorax, and with stalked eyes. 
Order 1. Schizopoda. Small thoracostracans with carapace covering 
entire 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 antenne 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. Solifuge. 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. 
