THE MOVEMENTS OF COPEPODA. 505 



The Movements of Copepoda. 



By 



E. IV. l^IacBride, 



Professor of Zoology, McGill University, Montreal. 



Since the time of Brady it has been generally supposed that 

 amongst the Copepoda the most important locomotor organs 

 were the antennules. This belief is categorically stated in 

 Huxley's text-book on ' The Anatomy of Invertebrated 

 Animals,' p. 235. 



During a stay of several weeks in the Plymouth Biological 

 Station I had almost daily opportunities of examining the 

 numerous Copepoda captured in the tow-net, and my observa- 

 tions are by no means consonant with the popularly accepted 

 idea. The movements of the species I examined were of two 

 kinds ; there was a slow gliding movement, and a sudden dart 

 of lightning swiftness. During the prosecution of movements 

 of the first description the antennules, or first antennae, are held 

 rigidly extended at right angles to the long axis of the body, 

 and their appearance suggests the idea that one of their func- 

 tions may be to act as hydrostatic sense-organs. Movement is 

 effected principally by means of the second antenna, the 

 gnathites likewise assisting, notably the second maxilla. It 

 seems probable that feeding is carried on during these slow 

 movements. 



The quick movements are effected, on the other hand, entirely 

 by the simultaneous action of the thoracic feet. A sudden 

 blow executed by all the four powerful pairs of paddles is suffi- 

 cient to propel the animal for a very considerable distance. 

 The animal moves so quickly during the longer darts that it is 



