232 J. M. D. OLMSTED 



glass rod by means of "orange sticky wax" and was thus enabled 

 to observe the effect of placing powdered carmine on the foot. 

 The grains of carmine were caught in the mucus and rapidly 

 conveyed posteriorly. I then teased bits of the foot and found 

 upon microscopical examination that long and vigorously beat- 

 ing cilia were present all over the surface of the foot. Those 

 along the edges seemed to beat the more vigorously. This, 

 so far as I know, is the first example of locomotion by ciliary 

 action alone reported for a marine gastropod. 



11. The foot of Haminea antillarum Orb. also exhibited no 

 waves This gastropod secretes a very large amount of mucus. 

 If one draws a glass rod along the bottom of the dish across the 

 animal's track, a centimeter or less behind the animal, it is 

 possible to swing the animals around by means of the tough 

 mucus thread which it has left behind itself. Carmine grains 

 sprinkled on the foot are carried posteriorly. Microscopic 

 examination of the teased foot showed cilia on all parts. 



12. Bulla occidentalis A. Ads. also has a ciliated foot and shows 

 no pedal waves. Bulla and Haminea move very much more 

 slowly than Marginella. Only one specimen of Bulla was found 

 The length of the foot was 1.3 cm. and the animal moved on an 

 average 1 cm. in 20.9 seconds. Haminea's rate is similar. 



In enumerating the types of gastropod locomotion, one should 

 not omit the peculiar swimming motion of the 'sea-hares/ such 

 as Aplysia limacina and Tethys dactyliomela. This is ac- 

 complished by wing-like appendages of the mantle, the para- 

 podia. The two gastropods named can also move over a surface 

 by means of retrograde pedal waves. 



The following outline gives the relations of all the types of 

 gastropod locomotion which have been described, with the ex- 

 ception of the gallop of Helix dupetithoutarsi (Carlson, '05, 

 Jordan, '05; Parker '11). 



