206 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



The antennae and claws of the second maxillipedes are 

 plunged into the tissues of the fish along with the teeth 

 of the maxilla, lacerating the skin, and into this wound 

 the suctorial mouth is directed. The blade-like mandibles 

 assist in collecting the particles of food material. These 

 are sucked up, pass down the oesophagus into the stomach, 

 where they are at once acted on by the fluid from the 

 digestive glands, and the colour of any blood present may 

 then be discharged. It is usually at the junction of the 

 oesophagus with the stomach that any red coloured 

 particles occur. The food can then be traced along the 

 stomach and intestine, and the waste matter is expelled 

 from the anus in long strings. 



On comparing transverse sections of the alimentary 

 canal of Lepteophtheirus and of Lerncea which happen to 

 contain food, and have been stained in eosin and hasma- 

 toxylin, there is seen to be a marked similarity in the 

 nature of the food in the two cases. Both are finely 

 granular, and stain red with eosin. Mucus from the 

 flounder has no such granular appearance. 



It is stated by some Zoologists that copepod parasites 

 are generally found most abundantly on weak and 

 diseased fishes. It is not so with Lepeophtheirus 

 pectoralis. Flounders with .many parasites in our tanks 

 were in as good condition as those that had none. They 

 were never found on flounders which were thin and in 

 poor condition, as they detach themselves and swim away 

 when the fish becomes feeble. This was proved by actual 

 experiments and observations at the Piel Hatchery. 



The Blood and Circulation. 



There is no heart in Lepeophtheirus, nor are there any 

 proper blood vessels. 



