236 J. M. D. OLMSTED 



mm. being observable. In all other cases a difference of at least 

 1 mm. could be seen with the exception of Eulota where the 

 waves passed in such rapid succession that only a slight movement 

 of the liquid could be detected. 



SUMMARY 



1. Three types of locomotion may be added to Vies ('07) 

 and Parker's ('11) classifications of gastropod locomotion, viz. 

 (1) lateral, (2) diagonal, and (3) composite. 



2. Cilia are the means of pedal locomotion in Marginella, 

 Haminea, and Bulla. 



3. Chiton and Fissurella are able to move backward without 

 reversing the normal direction of their pedal waves. 



4. Pedal waves can be shown by the use of a manometer 

 to be areas of suction and therefore concavities. 



LITERATURE CITED 



Biedermann, W. 1905 Studien zur vergleichenden Physiologie der peristal- 



tischen Bewegungen. II. Die locomotorischen Wellen der Schnecken- 



sohle. Arch. f. ges. Physiol., Bd. 107, pp. 1-56. 

 Carlson. A. J. 1905 The physiology of locomotion in gasteropods. Biol. 



Bull., vol. 8, pp. 85-92. 

 Jordan, H. 1901 Die Physiologie der Locomotion bei Aplysia limacina. Zeit. 



f. Biol. ,Bd. 41, pp. 196-238. 



1905 The physiology of locomotion in gasteropods. A reply to A. J. 



Carlson. Biol. Bull., vol. 9, pp. 138-140. 

 Kunkel, K. 1903 Zur Locomotion unserer Nacktschnecken. Zool. Anz., Bd. 



26, pp. 560-566. 

 Parker, G. H. 1911 The mechanism of locomotion in gasteropods. Jour. 



Morph., vol. 22, pp. 155-170. 



1914 The locomotion of Chiton. Contrib. from the Bermuda Biol. 



Station for Research. No. 31, 2 pp. 

 Uexkull, J. v. 1909 Umwelt und Innenwelt der Tiere. Berlin, 8vo, 261 pp. 

 Verrill, A. E. 1902 The Bermuda Islands. New Haven, Svo, x+ 548 pp., 40 



pis. 

 Vles, F. 1907 Sur les ondes pedieuses des Mollusques reptateurs. Compt. 



rend. Acad. Sci., Paris, tome 145, pp. 276-278. 



