742 



FRESH-WATER BIOLOGY 



Forbes commenced his series of papers. Although these papers 

 were not extensive, they were exact and carefully worked out, and 

 to Forbes may be given the credit of laying the foundation for all 

 subsequent work in this country. 



Though attractive in form, the Copepoda are complex in their 

 structure, and accurate classification can only be attained by care- 

 ful and laborious dissection, so that study of the order has been 

 neglected. 



With the exception of the Harpacticidae, all the free-swimming 

 Copepoda are characterized by a distinct division of the body into 

 cephalothorax and abdomen, the former being composed of five or 

 six segments and the latter of from three to five. The appendages 

 are as follows, commencing with the front of the animal: 



Frontalorgan 



Upper Zip^TJ-^""^' 

 Mandible F 

 Lower Lip'jtzL', 



First pair of antennae. 



Second pair of antennae. 



Mandibles. 



First maxillae. 



Second maxillae. 



Maxillipedes. 



First pair of swimming feet. 



Second pair of swimming feet. 



Third pair of swimming feet. 



Fourth pair of swimming feet. 



Fifth feet. 



Furcal rami. 



Fig. II 71. Diagrammatic figure of a female 

 Copepod. (After Giesbrecht and Schmeil.) 



Terminal Setae 

 Inner orJ)ortal Setae 



