PHYLUM ARTHROPODA — CLASS CRUSTACEA 265 



Order Copepoda, cyclops, fish louse (Argulus). 



Order Cirripedia, goose barnacle (Lepas), rock barnacle (Balanus), 

 Sacculma (Fig. 404). 



(Some authors prefer to rank Branchiopoda, Ostracoda, Copepoda, 

 and Cirripedia as subclasses, thereby dispensing with Entomostraca.) 



Subclass Malacostraca, pill bugs, sow bugs, sand fleas, lobsters, 

 craj^fish, and crabs. 



Order Isopoda, pill bugs and sow bugs. 



Order Amphipoda, sand fleas and beach fleas. 



Order Decapoda, crabs, crayfish, lobsters, and shrimps. 



Section II. Tracheata (tra ke a'ta, rough) both terrestrial and 

 aquatic arthropods which breathe by tracheae, book lungs or book 

 gills. This section is divided into three divisions depending on the 

 primitiveness of the characteristics. 



Division A. Prototracheata. The primitive form with some 

 arthropod characteristics and certain annelid features, such as 

 nephridia. 



Class II. Onychophora, Peripatus, the wormlike arthropod. 



Division B. Antennata. More highly specialized forms with one 

 pair of antennae. 



Class III. Myriapoda, centipedes and millepedes (thousand legs) 

 having one or two pairs of appendages on each segment. 



Order Chilopoda, centipedes. 



Order Diplopoda, millepedes. 



Class IV. Insecta, beetles, bees, locusts, etc., all with three pairs 

 of thoracic appendages and most of them with wings. 



Order Thysanura, silver moth. 



Order Collemhola, springtails. 



Order Ephemerida, mayflies. 



Order Odonata, dragonflies and damsel flies. 



Order Plecoptera, stone flies. 



Order Emhiidina, embicls. (Texas, California, Florida.) 



Order Orthoptera, crickets, grasshoppers, roaches. 



Order Isoptera, termites or "white ants." 



Order Dermaptera, earwigs. 



Order Coleoptera, weevils and beetles. 



Order Strepsiptera, stylopids (parasites in insects), 



Order Thysanoptera, thrips. 



