28 



ordinaiT leng'th and power, which pass obliquely back- 

 ward to the lateral margins of the carapace nearly opposite 

 the first pair of feet. The muscles of the first maxillse 

 are very short and thin. They pass along the posterior 

 surface of the muscles of the antenna, to the lateral 

 margins. The second maxilhie are controlled by powerful 

 muscles passing to the lateral margins. The muscles of 

 the first maxillipedes pass obliquely forward to the lateral 

 margins. The second maxillipedes are supplied with short 

 and powerful muscles which pass forward under the 

 second maxillfc. The terminal claw is provided with 

 muscles of great strength. The first three pairs of feet 

 are supplied with a complicated series of muscles passing 

 dorsally amongst those controlling the posterior portion 

 of the cephalo-thorax. The fourth pair of feet are 

 apparently little used, and consequently are only supplied 

 with feeble muscles. The alimentary canal is controlled 

 by longitudinal muscles, and also by muscles passing 

 transversely, which produce the wave-like peristaltic 

 motions and crenated appearance. The anus is opened 

 and shut by muscles passing obliquely, which open and 

 shut each side alternately or simultaneously according to 

 the requirements of the animal. The reproductive organs 

 are also controlled by muscles, which give rise to pulsating 

 movements, and assist in expelling the ova and 

 spermatophores. 



The Neevous System. 



The central nervous system in Lepeoj>htheirus consists 

 of a cerebral or supra-oesophageal ganglion and a large 

 sub-oesophageal ganglion placed on the ventral surface, 

 in the median line, and extending from slightly in front 

 of the second pair of maxillae to near the articulation of 

 the second pair of maxillipedes with the bodv. The 



