NOTES ON THE LOCOMOTION OF THE NUDIBRAN- 

 CHIATE MOLLUSK DENDRONOTUS GIGANTEUS 



O'DONOGHUE.* 



H. P. KJERSCHOW AGERSBORG. 



Many works have already appeared on molluscan locomotion. 

 Thus Simroth ('79) called attention to the relation between the 

 pedal nerve, the musculature of the foot, and the " locomotorischen 

 \Yellen " in Limax. Fleischmann ('85) observes :" Kontraktions- 

 wellen iiber die ganze Oberflache des Fusses in Anodonta, hinten 

 beginnend und nach vorn strichend." Jordan ('01), and again in 

 1905, records a similar feature for Aplysia limacina. Bohn ('02) 

 finds that progressive movements of Helix po mafia L. are accom- 

 plished by undulations in the form of waves of the pedal muscula- 

 ture which rests against a solid or support, and that these rhythmic 

 pedal waves are partly independent of mechanical excitations. 

 Kiinkel ('03) finds that the " Wellenspiel" increases when he 

 touches a crawling Limax tencllus (or L. agrcstris, L. arborum). 

 Carlson ('05) substantiates the findings of Jordan ('01) by de- 

 scribing for Helix dupetithonarsi a succession of large waves which 

 pass from the head to the tail, an extraordinary mode of progres- 

 sion employed when the animal is in a hurry. Biedermann ('05) 

 refers to " Querbander " that follow one another in parallel lines 

 on the under side of the foot of Helix pomatia, when this species 

 crawls on a glass plate. Von Uexkull ('09) confirms the findings 

 of Jordan for Aplysia, viz., that waves are advancing, when the 

 foot is lifted from the ground, from the anterior to the posterior, 

 the waves advancing in the opposite direction in Limax and Helix. 



A more complete analysis of pedal locomotion among mollusks 

 and other invertebrates has been accomplished by the brilliant 

 works of Parker ('n, '14, '17, '170, '21) and his pupil, Olmsted 

 ('17). Parker ('u) recognizes two main sets of locomotion 

 means for ordinary gastropods: (i) arhythmic (Ilyanssa obsolcta 



* Contribution from the Zoological Laboratory of the University of Illinois, 

 No. 200. 



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