LOCOMOTION OF BERMUDIAN MOLLUSKS 225 



rapping on its posterior third has no effect, unless perhaps to 

 make it move faster, while to tap the head causes the antennae 

 to be drawn in and the waves in the anterior half of the foot to 

 disappear at once Kiinkel C03) found a somewhat similar 

 reaction to be given by several species of slugs of the genus 

 Limax. If an actively creeping Limax is touched on the back 

 or on the side of the foot, the pedal waves cease for a moment, 

 after which the slug resumes its movement. Species of the slug 

 Arion, on the contrary, when stimulated in the same way, 

 cease wave movement and remain contracted for some time. 



2. Eulota simularis Fer., a snail found in exactly the same 

 habitat as Veronicella, has the same type of locomotion. I was 

 able to count the number of waves on the foot in two specimens 

 only. 



Eulota also shows similar reactions to Veronicella, for if a 

 moving Eulota is pushed forward by a thrust on the posterior 

 of the shell, locomotion proceeds normally and the tentacles 

 are not drawn in; but if the animal is pushed backward by a 

 thrust on the anterior of the shell, the pedal waves cease and the 

 anterior end of the foot loosens its hold on the substrate. 



3. Helcinia convexa Pfr., 4. Tethys dactylomela Rang. (cf. 

 .Jordan, '01), and 5. Fissurella nodosa Born show retrograde 

 monotaxic locomotion. 



6. Tectarius misricatus L. exhibits retrograde alternate ditaxic 

 locomotion. 



7. Tritonidea tincta var. bermudensis Dall affords an example 

 of retrograde tetrataxic locomotion. The foot of this snail is a 

 much smaller organ in proportion to the rest of the body than 

 that of other gastropods I have examined. Its average length 

 is 8 mm. and its width 2 mm. Running longitudinally down the 

 center of the foot is a fine white line hardly visible unless the 



