ARTHROPODA 



171 



Subclass Copepoda. — These Entomostraca have no shell and 

 lack abdominal appendages. They are among the most important 

 fish foods. Forms like Cyclops are the best known. The parasitic 

 guinea worm (page 96) is transmitted by Cyclops. The Copepoda 



Brood chamber 

 Heart- 



Abdom. 



Abdominal 



Abdo. 



Mandible 

 Anienna 



Anal 



Hepatic caeca 



|— Compound eye 

 ~ Ocellus 

 ^Antennule 



Labrum 



Fig. 75^^. Female Daphnia pulex, bearing summer eggs. 



Studies, vol. 11, 191 5.) 



(Dodds, Univ. of Colorado 



include many important fish parasites, the form Argulus being 

 parasitic on the carp. Dr. C. B. Wilson of the U. S. Bureau of 

 Fisheries is our international authority on parasitic Copepoda. 

 (Figure 76.) Lake Plankton is rich in the Copepod Diaptomus. 



Frontal or nan 



Uferus 



/ 

 / 



' ^Median eye 

 '^ .-/st. antenna 

 ^Paired eyes 



^Znd. antenna 



Caudal stylets' 



Fig. 755. Branchinecta packardii female showing uterus and eggs. (Dodds, Univ. 



of Colorado Studies, vol. 11, 191 5.) 



A number of species of Cyclops, colorless and blind, have been 

 found in wells. 



SublcassCirripedia. — The Cirripedia (Figure 77) include the com- 

 mon ^00 j-^w^-f/^ barnacle, Lepas, and the acorn barnacle, Balanus. The 

 latter are found along the coast attached to rocks and wharves where 



