56 OSWALD H. LATTER, M.A. 



the cilia covering the foot. "While the animal is in motion the foot 

 is first protruded somewhat slowly until it stretches a considerable 

 distance in front of the anterior margin of the shell, the cilia all 

 the while moving with great rapidity and appearing to "feel the 

 way." The foot having been protruded to its utmost extent, the 

 shell is drawn forward by a rapid muscular contraction. As soon 

 as this contraction commences, the cilia suddenly "cease moving and 

 stand out from the surface like the bristles of a brush absolutely 

 motionless and rigid. This condition is maintained until the foot 

 again commences to glide forward. I can offer no suggestion as 

 to the meaning or cause of this apparent rigidity other than that 

 the appearances are as though the pressure within the epithelial 

 cells becomes so great that the cilia cannot assume any other position 

 than one perpendicular to the surface, and forming a continuation or 

 the long axis of the cells on which they are severally carried. 



VII. Glochidia distasteful to Fish. 

 All fish with which I have experimented, viz., Perch, Loach, Stickle- 

 back, Minnow, have a strong dislike for Glochidia as an article of 

 food. They frequently seize a mass of Glochidia floating in the 

 disturbed water, but the mass is no sooner within the mouth than it 

 is forcibly and emphatically rejected, being spit out to a considerable 

 distance and very rarely (only once) attempted again. I do not 

 think that it is the irritation caused by Glochidia attaching them- 

 selves to the inside of the mouth which makes the fish behave thus, 

 for I killed six fishes which had tasted Glochidia within ten minutes 

 of making the experiment, and in only one of them did I find a 

 Glochidium attached to the mouth. There must, I think, be some 

 unpleasant odour or taste about the Glochidia ; or possibly the 

 " byssus," the shell-teeth, or both these latter combined, may 

 serve to make the Glochidia uninviting morsels. 



VIII. Powers of Resistance of Adult Anodon and Glochidia. 



An adult Anodon will live for at least a week, in cold weather, 

 after it has been removed from the shell. I consider the animal 

 alive so long as the cilia are beating and the heart is pulsating or 

 capable of responding to a moderate stimulus. The Glochidia will 

 live for a day or two within the gill of an apparently dead parent. 



